1.What are character constants in C++?
A "character constant" is
formed by enclosing a single character from the representable character set
within single quotation marks ('
'). Character constants are used to represent characters in
the execution character
set.
2.Write a program to add two strings without utilizing “+”
operator ?
#include<stdio.h>
void
main(void) {
char
str1[25],str2[25];
int i=0,j=0;
printf("\nEnter First String:");
gets(str1);
printf("\nEnter Second String:");
gets(str2);
while(str1[i]!='\0')
i++;
while(str2[j]!='\0')
{
str1[i]=str2[j];
j++;
i++; }
str1[i]='\0';
printf("\nConcatenated String is %s",str1);
}
3.Define the terms OSI, TCP, and IP.
OSI (pronounced as separate letters) is short
for Open System Interconnection.OSI is an ISO standard for
worldwide communications that defines a networking framework for implementing
protocols in seven layers.
Abbreviation of Transmission Control Protocol, and pronounced
as separate letters.TCP is one of the main protocols in TCP/IP
networks. Whereas the IP protocol deals only with packets, TCP enables
two hosts to establish a connection and exchange streams of data.
The Internet Protocol (IP) is the method or protocol
by which data is sent from one computer to another on the Internet. Each
computer (known as a host) on the Internet has at least one IP address
that uniquely identifies it from all other computers on the Internet.
4.What are streams in C++? What are predefined streams in
C++?
C++ also provides stream types for reading from and writing to files stored on disk. ... The types ifstream and ofstream are C++ stream classes designed to be connected to input or output files. File stream objects have all the member functions and manipulators possessed by the standard streams, cin and cout
Predefined Streams in C++:
|
Narrow character
stream |
Wide character
stream |
Associated C standard
files |
|
cin
|
wcin
|
stdin
|
|
cout
|
wcout
|
stdout
|
|
cerr
|
wcerr
|
stderr
|
|
clog
|
wclog
|
stderr
|
5.Give me a Query to find out the second largest
compensation in an organization ?
Consider the following table for example:
Name Salary
---------------
abc 100000
bcd 1000000
efg 40000
ghi 500000
The query will be as follows:
SELECT name, MAX(salary) AS
salary FROM employee WHERE salary <
(SELECT MAX(salary) FROM
employee);
What is the implementation of merge ?
Steps to implement
Merge Sort:
1) Divide the unsorted array into n partitions, each partition contains 1 element. Here the one element is considered as sorted.
2) Repeatedly merge partitioned units to produce new sublists until there is only 1 sublist remaining. This will be the sorted list at the end.
1) Divide the unsorted array into n partitions, each partition contains 1 element. Here the one element is considered as sorted.
2) Repeatedly merge partitioned units to produce new sublists until there is only 1 sublist remaining. This will be the sorted list at the end.
Merge sort is a
fast, stable sorting routine with guaranteed O(n*log(n)) efficiency. When
sorting arrays, merge sort requires additional scratch space proportional to
the size of the input array.
C Language :
1) How do you construct an increment statement or decrement statement in C?
Answer:There are actually two ways you can do this. One is to
use the increment operator ++ and decrement operator –. For example, the statement “x++” means to increment
the value of x by 1. Likewise, the statement “x –” means to decrement the value
of x by 1. Another way of writing increment statements is to use the
conventional + plus sign or – minus
sign. In the case of “x++”, another way to write it is “x = x +1?.
2) Some coders debug their programs by placing comment symbols
on some codes instead of deleting it. How does this aid in debugging?
Answer:Placing comment symbols /* */ around a code, also
referred to as “commenting out”, is a way of
isolating some codes that you think maybe causing errors in the program,
without deleting the code. The idea is that if the code is in
fact correct, you simply remove the comment symbols and continue on. It also
saves you time and effort on having to retype the codes if you have deleted it
in the first place.
3) What is the equivalent code of the following statement in
WHILE LOOP format?
[c]
for (a=1; a<=100; a++)
printf ("%d\n", a * a);
[/c]
[c]
for (a=1; a<=100; a++)
printf ("%d\n", a * a);
[/c]
Answer:[c]
a=1;
while (a<=100) {
printf ("%d\n", a * a);
a++;
}
[/c]
a=1;
while (a<=100) {
printf ("%d\n", a * a);
a++;
}
[/c]
4) What is spaghetti programming?
Answer:Spaghetti programming refers to codes that tend to get
tangled and overlapped throughout the program. This unstructured approach to
coding is usually attributed to lack of experience on the part of the
programmer. Spaghetti programing makes a program complex and analyzing the
codes difficult, and so must be avoided as much as possible.
5) In C programming, how do you insert quote characters (‘ and “) into the output screen?
Answer:This is a common problem for beginners because quotes are
normally part of a printf statement. To insert the quote character as part of
the output, use the format specifiers \’
(for single quote), and \” (for double quote).
6) What is the use of a ‘\0' character?
Answer:It is referred to as a terminating null character, and is
used primarily to show the end of a string value.
7) What is the difference between the = symbol and == symbol?
Answer:The = symbol is often used in mathematical operations. It
is used to assign a value to a given variable. On the other hand, the ==
symbol, also known as “equal to” or “equivalent to”, is a
relational operator that is used to compare two values.
8) Which of the following operators is incorrect and why? (
>=, <=, <>, ==)
Answer:<> is incorrect. While this operator is correctly
interpreted as “not equal to” in writing
conditional statements, it is not the proper operator to be used in C
programming. Instead, the operator != must be used to indicate “not equal to” condition.
9) Can the curly brackets { } be used to enclose a single line
of code?
Answer:While curly brackets are mainly used to group several
lines of codes, it will still work without error if you used it for a single
line. Some programmers prefer this method as a way of organizing codes to make
it look clearer, especially in conditional statements.
10) What are header files and what are its uses in C programming?
Answer:Header files are also known as library files. They
contain two essential things: the definitions and prototypes of functions being
used in a program. Simply put, commands that you use in C programming are
actually functions that are defined from within each header files. Each header
file contains a set of functions. For example: stdio.h is a header file that
contains definition and prototypes of commands like printf and scanf.
11) Can I use “int” data type to store the value 32768? Why?
Answer:No. “int” data type is capable of
storing values from -32768 to 32767. To store 32768, you can use “long int”
instead. You can also use “unsigned int”, assuming you don’t intend to store
negative values.
12) Can two or more operators such as \n and \t be combined in a
single line of program code
Answer:Yes, it’s perfectly
valid to combine operators, especially if the need arises. For example: you can
have a code like ” printf (“Hello\n\n\’World\’”) ” to output the text “Hello”
on the first line and “World” enclosed in single quotes to appear on
the next two lines.
13) Why is it that not all header files are declared in every C
program?
Answer:The choice of declaring a header file at the top of each
C program would depend on what commands/functions you will be using in that
program. Since each header file contains different function definitions and
prototype, you would be using only those header files that would contain the
functions you will need. Declaring all header files in every program would only
increase the overall file size and load of the program, and is not considered a
good programming style.
14) When is the “void” keyword used in a function?
Answer:When declaring functions, you will decide whether that
function would be returning a value or not. If that function will not return a
value, such as when the purpose of a function is to display some outputs on the
screen, then “void” is to be placed at the
leftmost part of the function header. When a return value is expected after the
function execution, the data type of the return value is placed instead of “void”.
15) What are compound statements?
Answer:Compound statements are made up of two or more program
statements that are executed together. This usually occurs while handling conditions
wherein a series of statements are executed when a TRUE or FALSE is evaluated.
Compound statements can also be executed within a loop. Curly brackets { } are
placed before and after compound statements.
16) Write a loop statement that will show the following output:
1
12
123
1234
12345
Answer:[c]
for (a=1; a<=5; i++) {
for (b=1; b<=a; b++)
printf("%d",b);
printf("\n");
}
[/c]
1
12
123
1234
12345
Answer:[c]
for (a=1; a<=5; i++) {
for (b=1; b<=a; b++)
printf("%d",b);
printf("\n");
}
[/c]
17) What is wrong in this statement? scanf(“%d”,whatnumber);
Answer:An ampersand & symbol must be placed before the variable
name whatnumber. Placing & means whatever integer value is entered by the
user is stored at the “address” of the variable name.
This is a common mistake for programmers, often leading to logical errors.
18) How do you generate random numbers in C?
Answer:Random numbers are generated in C using the rand()
command. For example: anyNum = rand() will generate any integer number
beginning from 0, assuming that anyNum is a variable of type integer.
19) What could possibly be the problem if a valid function name
such as tolower() is being reported by the C compiler as undefined?
The most probable reason behind this error is that the header file for that function was not indicated at the top of the program. Header files contain the definition and prototype for functions and commands used in a C program. In the case of “tolower()”, the code “#include ” must be present at the beginning of the program.
The most probable reason behind this error is that the header file for that function was not indicated at the top of the program. Header files contain the definition and prototype for functions and commands used in a C program. In the case of “tolower()”, the code “#include ” must be present at the beginning of the program.
20) What does the format %10.2 mean when included in a printf
statement?
Answer:This format is used for two things: to set the number of
spaces allotted for the output number and to set the number of decimal places.
The number before the decimal point is for the allotted space, in this case it
would allot 10 spaces for the output number. If the number of space occupied by
the output number is less than 10, addition space characters will be inserted
before the actual output number. The number after the decimal point sets the
number of decimal places, in this case, it’s
2 decimal spaces.
21) What is wrong with this statement? myName = “Robin”;
Answer:You cannot use the = sign to assign values to a string
variable. Instead, use the strcpy function. The correct statement would be:
strcpy(myName, “Robin”);
22) How do you determine the length of a string value that was stored in a variable?
Answer:To get the length of a string value, use the function
strlen(). For example, if you have a variable named FullName, you can get the
length of the stored string value by using this statement: I =
strlen(FullName); the variable I will now have the character length of the
string value.
23) Is it possible to initialize a variable at the time it was
declared?
Answer: Yes, you don’t
have to write a separate assignment statement after the variable
declaration, unless you plan to change it later on. For example: char
planet[15] = “Earth”; does two things: it
declares a string variable named planet, then initializes it with the value
“Earth”.
24) What are the different file extensions involved when
programming in C?
Answer: Source codes in C are saved with .C file extension.
Header files or library files have the .H file extension. Every time a program
source code is successfully compiled, it creates an .OBJ object file, and an
executable .EXE file.
25) What are reserved words?
Answer: Reserved words are words that are part of the standard C
language library. This means that reserved words have special meaning and
therefore cannot be used for purposes other than what it is originally intended
for. Examples of reserved words are int, void, and return.
26) What are linked list?
Answer:A linked list is composed of nodes that are connected
with another. In C programming, linked lists are created using pointers. Using
linked lists is one efficient way of utilizing memory for storage.
(CLICK HERE FOR MORE DETAILS ON Linked List )
27) What are binary trees?
Answer:Binary trees are actually an extension of the concept of
linked lists. A binary tree has two pointers, a left one and a right one. Each
side can further branch to form additional nodes, which each node having two
pointers as well.
28) Not all reserved words are written in lowercase. TRUE or
FALSE?
Answer:FALSE. All reserved words must be written in lowercase;
otherwise the C compiler would interpret this as unidentified and invalid.
29) What is wrong with this program statement? void = 10;
Answer:The word void is a reserved word in C language. You
cannot use reserved words as a user-defined variable.
30) Is this program statement valid? INT = 10.50;
Answer:Assuming that INT is a variable of type float, this
statement is valid. One may think that INT is a reserved word and must not be
used for other purposes. However, recall that reserved words are express in
lowercase, so the C compiler will not interpret this as a reserved word.
31) What is a newline escape sequence?
Answer:A newline escape sequence is represented by the \n
character. This is used to insert a new line when displaying data in the output
screen. More spaces can be added by inserting more \n characters. For example,
\n\n would insert two spaces. A newline escape sequence can be placed before
the actual output expression or after.
32) What is output redirection?
Answer:It is the process of transferring data to an alternative
output source other than the display screen. Output redirection allows a program
to have its output saved to a file. For example, if you have a program named
COMPUTE, typing this on the command line as COMPUTE >DATA can accept input
from the user, perform certain computations, then have the output redirected to
a file named DATA, instead of showing it on the screen.
33) What is the difference between functions abs() and fabs()?
Answer:These 2 functions basically perform the same action,
which is to get the absolute value of the given value. Abs() is used for
integer values, while fabs() is used for floating type numbers. Also, the
prototype for abs() is under , while fabs() is under .
34) Write a simple code fragment that will check if a number is
positive or negative.
Answer:[c]
If (num>=0)
printf("number is positive");
else
printf ("number is negative");
[/c]
printf("number is positive");
else
printf ("number is negative");
[/c]
35) What does the function toupper() do?
Answer:It is used to convert any letter to its upper case mode.
Toupper() function prototype is declared in . Note that this function will
only convert a single character, and not an entire string.
36) Which function in C can be used to append a string to
another string?
Answer:The strcat function. It takes two parameters, the source
string and the string value to be appended to the source string.
37) Dothese two program statements perform the same output? 1)
scanf(“%c”, &letter); 2)
letter=getchar()
Answer:Yes, they both do the exact same thing, which is to
accept the next key pressed by the user and assign it to variable named letter.
38) What is the difference between text files and binary files?
Answer:Text files contain data that can easily be understood by
humans. It includes letters, numbers and other characters. On the other hand,
binary files contain 1s and 0s that only computers can interpret.
39) is it possible to create your own header files?
Answer:Yes, it is possible to create a customized header file.
Just include in it the function prototypes that you want to use in your
program, and use the #include directive followed by the name of your header
file.
40) What is dynamic data structure?
Answer:Dynamic data structure provides a means for storing data
more efficiently into memory. Using dynamic memory allocation, your program
will access memory spaces as needed. This is in contrast to static data
structure, wherein the programmer has to indicate a fix number of memory space
to be used in the program.
41) The % symbol has a special use in a printf statement. How
would you place this character as part of the output on the screen?
Answer:You can do this by using %% in the printf statement. For
example, you can write printf(“10%%”) to
have the output appear as 10% on the screen.
42) What are the advantages and disadvantages of a heap?
Answer:Storing data on the heap is slower than it would take
when using the stack. However, the main advantage of using the heap is its
flexibility. That’s because memory in this structure
can be allocated and remove in any particular order. Slowness in the heap
can be compensated if an algorithm was well designed and implemented.
CTS Database Questions
for Degree Students:
1. What is database?
A database is a collection of information that is
organized. So that it can easily be accessed, managed, and updated.
2. What is DBMS?
DBMS stands for Database Management System. It is a collection
of programs that enables user to create and maintain a database.
3. What is a Database system?
The database and DBMS software together is called as Database
system.
4. What are the advantages of DBMS?
I. Redundancy is controlled.
II. Providing multiple user interfaces.
III. Providing backup and recovery
IV. Unauthorized access is restricted.
V. Enforcing integrity constraints.
5. What is normalization?
It is a process of analysing the given relation schemas based on
their Functional Dependencies (FDs) and primary key to achieve the properties
(1).Minimizing redundancy, (2). Minimizing insertion, deletion and update anomalies.
(1).Minimizing redundancy, (2). Minimizing insertion, deletion and update anomalies.
6. What is Data Model?
A collection of conceptual tools for describing data, data relationships data semantics and constraints.
A collection of conceptual tools for describing data, data relationships data semantics and constraints.
7. What is E-R model?
This data model is based on real world that consists of basic
objects called entities and of relationship among these objects. Entities
are described in a database by a set of attributes.
8. What is Object Oriented model?
This model is based on collection of objects. An object contains
values stored in instance variables with in the object. An object also contains
bodies of code that operate on the object. These bodies of code are called
methods. Objects that contain same types of values and the same methods are
grouped together into classes.
9. What is an Entity?
An entity is a thing or object of importance about which data must be captured.
An entity is a thing or object of importance about which data must be captured.
10. What is DDL (Data Definition Language)?
A data base schema is specifies by a set of definitions
expressed by a special language called DDL.
11. What is DML (Data Manipulation Language)?
This language that enable user to access or manipulate data as
organised by appropriate data model. Procedural DML or Low level: DML
requires a user to specify what data are needed and how to get those data.
Non-Procedural DML or High level: DML requires a user to specify what data are
needed without specifying how to get those data
12. What is DML Compiler?
It translates DML statements in a query language into low-level
instruction that the query evaluation engine can understand.
13. What is Query evaluation engine?
It executes low-level instruction generated by compiler.
14. What is Functional Dependency?
Functional Dependency is the starting point of normalization.
Functional Dependency exists when a relation between two attributes allows you
to uniquely determine the corresponding attribute’s value.
15. What is 1 NF (Normal Form)?
The first normal form or 1NF is the first and the simplest type
of normalization that can be implemented in a database. The main aims of 1NF
are to:
1. Eliminate duplicative columns from the same table.
2. Create separate tables for each group of related data and
identify each row with a unique column (the primary key).
16. What is Fully Functional dependency?
A functional dependency X Y is full functional dependency if
removal of any attribute A from X means that the dependency does not hold any
more.
17. What is 2NF?
A relation schema R is in 2NF if it is in 1NF and every
non-prime attribute A in R is fully functionally dependent on primary key.
18. What is 3NF?
A relation is in third normal form if it is in Second Normal
Form and there are no functional (transitive) dependencies between two (or
more) non-primary key attributes.
19. What is BCNF (Boyce-Codd Normal Form)?
A table is in Boyce-Codd normal form (BCNF) if and only if it is
in 3NF and every determinant is a candidate key.
20. What is 4NF?
Fourth normal form requires that a table be BCNF and contain no
multi-valued dependencies.
21. What is 5NF?
A table is in fifth normal form (5NF) or Project-Join Normal
Form (PJNF) if it is in 4NF and it cannot have a lossless decomposition into
any number of smaller tables.
22. What is a query?
A query with respect to DBMS relates to user commands that are
used to interact with a data base.
23. What is meant by query optimization?
The phase that identifies an efficient execution plan for
evaluating a query that has the least estimated cost is referred to as query
optimization.
24. What is an attribute?
It is a particular property, which describes the entity.
It is a particular property, which describes the entity.
25. What is RDBMS?
Relational Data Base Management Systems (RDBMS) are database
management systems that maintain data records and indices in tables.
26. What’s
difference between DBMS and RDBMS?
DBMS provides a systematic and organized way of storing,
managing and retrieving from collection of logically related information. RDBMS
also provides what DBMS provides but above that it provides relationship
integrity.
27. What is SQL?
SQL stands for Structured Query Language. SQL is an ANSI
(American National Standards Institute) standard computer language for
accessing and manipulating database systems. SQL statements are used to retrieve
and update data in a database.
28. What is Stored Procedure?
A stored procedure is a named group of SQL statements that have
been previously created and stored in the server database.
29. What is a view?
A view may be a subset of the database or it may contain virtual
data that is derived from the database files but is not explicitly stored.
30. What is Trigger?
A trigger is a SQL procedure that initiates an action when an
event (INSERT, DELETE or UPDATE) occurs.
31. What is Index?
An index is a physical structure containing pointers to the
data.
32. What is extension and intension?
Extension -It is the number of tuples present in a table at any
instance. This is time dependent.
Intension -It is a constant value that gives the name, structure
of table and the constraints laid on it.
33. What do you mean by atomicity and aggregation?
Atomicity-Atomicity states that database modifications must
follow an “all or nothing” rule. Each
transaction is said to be “atomic.” If one part of the transaction
fails, the entire transaction fails.
Aggregation - A feature of the entity relationship model that
allows a relationship set to participate in another relationship set. This is
indicated on an ER diagram by drawing a dashed box around the aggregation.
34. What is RDBMS KERNEL?
Two important pieces of RDBMS architecture are the kernel, which
is the software, and the data dictionary, which consists of the system- level
data structures used by the kernel to manage the database.
35. Name the sub-systems of a RDBMS?
I/O, Security, Language Processing, Process Control,
Storage Management, Logging and Recovery, Distribution
Control, Transaction Control, Memory Management, Lock Management.
36. How do you communicate with an RDBMS?
You communicate with an RDBMS using Structured Query Language
(SQL)
37. Disadvantage in File Processing System?
· Data redundancy
& inconsistency.
· Difficult in
accessing data.
· Data isolation.
· Data integrity.
· Concurrent access is
not possible.
· Security Problems.
38. What is VDL (View Definition Language)?
It specifies user views and their mappings to the conceptual
schema.
39. What is SDL (Storage Definition Language)?
This language is to specify the internal schema. This language
may Specify the mapping between two schemas.
40. Describe concurrency control?
Concurrency control is the process managing simultaneous
operations against a database so that database integrity is no compromised.
There are two approaches to concurrency control.
The pessimistic approach involves locking and the optimistic
approach involves versioning.
41. Describe the difference between homogeneous and
heterogeneous distributed database?
A homogenous database is one that uses the same DBMS at each
node. A heterogeneous database is one that may have a different DBMS at each
node.
42. What is a distributed database?
A distributed database is a single logical database that is
spread across more than one node or locations that are all connected via some
communication link.
43. Explain the difference between two and three-tier
architectures?
Three-tier architecture includes a client and two server layers.
The application code is stored on the application
server and the database is stored on the database server. A
two-tier architecture includes a client and one server layer. The database is
stored on the database server.
44. Briefly describe the three types of SQL commands?
Data definition language commands are used to create, alter, and
drop tables. Data manipulation commands are used to insert, modify, update, and
query data in the database. Data control language commands help the DBA to
control the database.
45. List some of the properties of a relation?
Relations in a database have a unique name and no multivalued
attributes exist. Each row is unique and each attribute within a relation has a
unique name. The sequence of both columns and rows is irrelevant.
46. Explain the differences between an intranet and an extranet?
An Internet database is accessible by everyone who has access to
a Web site. An intranet database limits access to only people within a given
organization.
47. What is SQL Deadlock?
Deadlock is a unique situation in a multi user system that
causes two or more users to wait indefinitely for a locked resource.
48. What is a Catalog?
A catalog is a table that contains the information such as
structure of each file, the type and storage format of each data item and
various constraints on the data .The information stored in the catalog is
called Metadata.
49. What is data ware housing & OLAP?
Data warehousing and OLAP (online analytical processing) systems
are the techniques used in many companies to extract and analyze
useful information from very large databases for decision making .
50. Describe the three levels of data abstraction?
Physical level: The lowest level of abstraction describes how
data are stored.
Logical level: The next higher level of abstraction, describes
what data are stored in database and what relationship among those data.
View level: The highest level of abstraction describes only part
of entire database.
51. What is Data Independence?
Data independence means that the application is independent of
the storage structure and access strategy of data.
52. How many types of relationship exist in database designing?
There are three major relationship models:-
One-to-one
One-to-many
Many-to-many
53. What is order by clause?
ORDER BY clause helps to sort the data in either ascending order
to descending
54. What is the use of DBCC commands?
DBCC stands for database consistency checker. We use these
commands to check the consistency of the databases, i.e.,
maintenance, validation task and status checks.
55. What is Collation?
Collation refers to a set of rules that determine how data is
sorted and compared.
56. What is difference between DELETE & TRUNCATE commands?
Delete command removes the rows from a table based on the
condition that we provide with a WHERE clause. Truncate will actually remove
all the rows from a table and there will be no data in the table after we run
the truncate command.
57. What is Hashing technique?
This is a primary file organization technique that provides very
fast access to records on certain search conditions.
58. What is a transaction?
A transaction is a logical unit of database processing that
includes one or more database access operations.
59. What are the different phases of Transaction?
Analysis phase
Redo phase
Undo phase
60. What is “transparent
dbms”?
It is one, which keeps its physical structure hidden from user.
61. What are the primitive operations common to all record
management System?
Addition, deletion and modification.
62. Explain the differences between structured data and
unstructured data.
Structured data are facts concerning objects and events. The
most important structured data are numeric, character, and dates.
Structured data are stored in tabular form. Unstructured data
are multimedia data such as documents, photographs, maps, images, sound, and
video clips. Unstructured data are most commonly found on Web servers and
Web-enabled databases.
63. What are the major functions of the database administrator?
Managing database structure, controlling concurrent processing,
managing processing rights and responsibilities, developing database security,
providing for database recovery, managing the DBMS and maintaining the data
repository.
64. What is a dependency graph?
A dependency graph is a diagram that is used to portray the
connections between database elements.
65. Explain the difference between an exclusive lock and a
shared lock?
An exclusive lock prohibits other users from reading the locked
resource; a shared lock allows other users to read the locked resource, but
they cannot update it.
66. Explain the "paradigm mismatch" between SQL and
application programming languages.
SQL statements return a set of rows, while an application
program works on one row at a time. To resolve this mismatch the results of
SQL statements are processed as pseudofiles, using a cursor or pointer to
specify which row is being processed.
67. Name four applications for triggers.
(1)Providing default values, (2) enforcing data constraints,
(3) Updating views and (4) enforcing referential integrity
68. What are the advantages of using stored procedures?
The advantages of stored procedures are (1) greater security,
(2) decreased network traffic, (3) the fact that SQL can be optimized and (4)
code sharing which leads to less work, standardized processing, and
specialization among developers.
69. Explain the difference between attributes and identifiers.
Entities have attributes. Attributes are properties that
describe the entity's characteristics. Entity instances have identifiers.
Identifiers are attributes that name, or identify, entity instances.
70. What is Enterprise Resource Planning (ERP), and what kind of
a database is used in an ERP application?
Enterprise Resource Planning (ERP) is an information system used
in manufacturing companies and includes sales, inventory, production planning,
purchasing and other business functions. An ERP system typically uses a
multiuser database.
71. Describe the difference between embedded and dynamic SQL?
Embedded SQL is the process of including hard coded SQL
statements. These statements do not change unless the source code is modified.
Dynamic SQL is the process of generating SQL on the fly.The statements
generated do not have to be the same each time.
72. Explain a join between tables
A join allows tables to be linked to other tables when a
relationship between the tables exists. The relationships are established by
using a common column in the tables and often uses the primary/foreign key
relationship.
73. Describe a subquery.
A subquery is a query that is composed of two queries. The first
query (inner query) is within the WHERE clause of the other query (outer
query).
74. Compare a hierarchical and network database model?
The hierarchical model is a top-down structure where each parent
may have many children but each child can have only one parent. This model
supports one-to-one and one-to-many relationships.
The network model can be much more flexible than the
hierarchical model since each parent can have multiple children but each child
can also have multiple parents. This model supports one-to-one, one-to-many,
and many-to-many relationships.
75. Explain the difference between a dynamic and materialized
view.
A dynamic view may be created every time that a specific view is
requested by a user. A materialized view is created and or updated infrequently
and it must be synchronized with its associated base table(s).
76. Explain what needs to happen to convert a relation to third
normal form.
First you must verify that a relation is in both first normal
form and second normal form. If the relation is not, you must convert into
second normal form. After a relation is in second normal form, you must remove
all transitive dependencies.
77. Describe the four types of indexes?
A unique primary index is unique and is used to find and store a
row. A nonunique primary index is not unique and is used to find a row but also
where to store a row (based on its unique primary index). A unique secondary
index is unique for each row and used to find table rows. A nonunique secondary
index is not unique and used to find table rows.
78. Explain minimum and maximum cardinality?
Minimum cardinality is the minimum number of instances of an
entity that can be associated with each instance of another entity. Maximum
cardinality is the maximum number of instances of an entity that can be
associated with each instance of another entity.
79. What is deadlock? How can it be avoided? How can it be
resolved once it occurs?
Deadlock occurs when two transactions are each waiting on a
resource that the other transaction holds. Deadlock can be prevented by
requiring transactions to acquire all locks at the same time; once it occurs,
the only way to cure it is to abort one of the transactions and back out of
partially completed work.
80. Explain what we mean by an ACID transaction.
An ACID transaction is one that is atomic, consistent, isolated,
and durable. Durable means that database changes are permanent. Consistency can
mean either statement level or transaction level consistency. With transaction
level consistency, a transaction may not see its own changes.Atomic means it is
performed as a unit.
81. Under what conditions should indexes be used?
Indexes can be created to enforce uniqueness, to facilitate
sorting, and to enable fast retrieval by column values. A good candidate for an
index is a column that is frequently used with equal conditions in WHERE
clauses.
82. What is difference between SQL and SQL SERVER?
SQL is a language that provides an interface to RDBMS, developed
by IBM. SQL SERVER is a RDBMS just like Oracle, DB2.
83. What is Specialization?
It is the process of defining a set of subclasses of an entity
type where each subclass contain all the attributes and relationships of the
parent entity and may have additional attributes and relationships which are
specific to itself.
84. What is generalization?
It is the process of finding common attributes and relations of
a number of entities and defining a common super class for them.
85. What is meant by Proactive, Retroactive and Simultaneous
Update?
Proactive Update: The updates that are applied to database
before it becomes effective in real world.
Retroactive Update: The updates that are applied to database
after it becomes effective in real world.
Simultaneous Update: The updates that are applied to database at
the same time when it becomes effective in real world.
86. What is RAID Technology?
Redundant array of inexpensive (or independent) disks. The main goal of raid technology is to even out the widely different rates of performance improvement of disks against those in memory and microprocessor. Raid technology employs the technique of data striping to achieve higher transfer rates.
87. What are serial, non serial schedule?
A schedule S is serial if, for every transaction T participating
in the schedule, all the operations of T is executed consecutively in the
schedule, otherwise, the schedule is called non-serial schedule.
88. What are conflict serializable schedules?
A schedule S of n transactions is serializable if it is
equivalent to some serial schedule of the same n transactions.
89. What is view serializable?
A schedule is said to be view serializable if it is view
equivalent with some serial schedule.
90. What is a foreign key?
A key of a relation schema is called as a foreign key if it is
the primary key of
some other relation to which it is related to.
some other relation to which it is related to.
91. What are the disadvantages of using a dbms?
1) High initial investments in h/w, s/w, and training.
2) Generality that a DBMS provides for defining and processing data.
3) Overhead for providing security, concurrency control, recovery, and integrity functions.
2) Generality that a DBMS provides for defining and processing data.
3) Overhead for providing security, concurrency control, recovery, and integrity functions.
92. What is Lossless join property?
It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition.
It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition.
93. What is a Phantom Deadlock?
In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to identify deadlocks that do not really exist. Such situations are called phantom deadlocks and they lead to unnecessary aborts.
In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to identify deadlocks that do not really exist. Such situations are called phantom deadlocks and they lead to unnecessary aborts.
94. What is a checkpoint and When does it occur?
A Checkpoint is like a snapshot of the DBMS state. By taking checkpoints, the DBMS can reduce the amount of work to be done during restart in the event of subsequent crashes.
A Checkpoint is like a snapshot of the DBMS state. By taking checkpoints, the DBMS can reduce the amount of work to be done during restart in the event of subsequent crashes.
95. What is schema?
The description of a data base is called the database schema , which is specified during database design and is not expected to change frequently . A displayed schema is called schema diagram .We call each object in the schema as schema construct.
The description of a data base is called the database schema , which is specified during database design and is not expected to change frequently . A displayed schema is called schema diagram .We call each object in the schema as schema construct.
Java Questions:
1.What is JVM?
The Java interpreter along with the runtime environment required
to run the Java application in called as Java virtual machine(JVM)
2. What is the most important feature of Java?
Java is a platform independent language.
3. What do you mean by platform independence?
Platform independence means that we can write and compile the
java code in one platform (eg Windows) and can execute the class in any other
supported platform eg (Linux,Solaris,etc).
4. What is the difference between a JDK and a JVM?
JDK is Java Development Kit which is for development purpose and
it includes execution environment also. But JVM is purely a run time
environment and hence you will not be able to compile your source files using a
JVM.
5. What is the base class of all classes?
java.lang.Object
6. What are the access modifiers in Java?
There are 3 access modifiers. Public, protected and private, and
the default one if no identifier is specified is called friendly, but
programmer cannot specify the friendly identifier explicitly.
7. What is are packages?
A package is a collection of related classes and interfaces
providing access protection and namespace management.
8. What is meant by Inheritance and what are its advantages?
Inheritance is the process of inheriting all the features
from a class. The advantages of inheritance are reusability of code and
accessibility of variables and methods of the super class by subclasses.
9. What is the difference between superclass and subclass?
A super class is a class that is inherited whereas sub
class is a class that does the inheriting.
10. What is an abstract class?
An abstract class is a class designed with implementation gaps
for subclasses to fill in and is deliberately incomplete.
11. What are the states associated in the thread?
Thread contains ready, running, waiting and dead states.
12. What is synchronization?
Synchronization is the mechanism that ensures that only one
thread is accessed the resources at a time.
13. What is deadlock?
When two threads are waiting each other and can’t precede the
program is said to be deadlock.
14. What is an applet?
Applet is a dynamic and interactive program that runs inside a
web page displayed by a java capable browser
15. What is the lifecycle of an applet?
init() method - Can be called when an applet is first loaded
start() method - Can be called each time an applet is started.
paint() method - Can be called when the applet is minimized or maximized.
stop() method - Can be used when the browser moves off the applet’s page.
destroy() method - Can be called when the browser is finished with the applet.
start() method - Can be called each time an applet is started.
paint() method - Can be called when the applet is minimized or maximized.
stop() method - Can be used when the browser moves off the applet’s page.
destroy() method - Can be called when the browser is finished with the applet.
16. How do you set security in applets?
using setSecurityManager() method
17. What is a layout manager and what are different types of layout managers available in java AWT?
A layout manager is an object that is used to organize
components in a container. The different layouts are available are FlowLayout,
BorderLayout, CardLayout, GridLayout and GridBagLayout
18. What is JDBC?
JDBC is a set of Java API for executing SQL statements. This API
consists of a set of classes and interfaces to enable programs to write pure
Java Database applications.
19. What are drivers available?
-a) JDBC-ODBC Bridge driver b) Native API Partly-Java driver
c) JDBC-Net Pure Java driver d) Native-Protocol Pure Java driver
c) JDBC-Net Pure Java driver d) Native-Protocol Pure Java driver
20. What is stored procedure?
Stored procedure is a group of SQL statements that forms a
logical unit and performs a particular task. Stored Procedures are used to
encapsulate a set of operations or queries to execute on database. Stored
procedures can be compiled and executed with different parameters and results
and may have any combination of input/output parameters.
21. What is the Java API?
The Java API is a large collection of ready-made software
components that provide many useful capabilities, such as graphical user
interface (GUI) widgets.
22. Why there are no global variables in Java?
Global variables are globally accessible. Java does not support
globally accessible variables due to following reasons:
1)The global variables breaks the referential transparency
2)Global variables creates collisions in namespace.
1)The global variables breaks the referential transparency
2)Global variables creates collisions in namespace.
23. What are Encapsulation, Inheritance and Polymorphism?
Encapsulation is the mechanism that binds together code
and data it manipulates and keeps both safe from outside interference and
misuse. Inheritance is the process by which one object acquires the properties
of another object. Polymorphism is the feature that allows one interface to be
used for general class actions.
24. What is the use of bin and lib in JDK?
Bin contains all tools such as javac, appletviewer, awt tool,
etc., whereas lib contains API and all packages.
25. What is method overloading and method overriding?
Method overloading: When a method in a class having the same
method name with different arguments is said to be method overloading. Method
overriding : When a method in a class having the same method name with same
arguments is said to be method overriding.
26. What is the difference between this() and super()?
this() can be used to invoke a constructor of the same class
whereas super() can be used to invoke a super class constructor.
27. What is Domain Naming Service(DNS)?
It is very difficult to remember a set of numbers(IP address) to
connect to the Internet. The Domain Naming Service(DNS) is used to overcome
this problem. It maps one particular IP address to a string of characters. For
example, www. mascom. com implies com is the domain name reserved for US
commercial sites, moscom is the name of the company and www is the name of the
specific computer, which is mascom’s server.
28. What is URL?
URL stands for Uniform Resource Locator and it points to resource
files on the Internet. URL has four components: http://www. address.
com:80/index.html, where http - protocol name, address - IP address or host
name, 80 - port number and index.html - file path.
29. What is RMI and steps involved in developing an RMI object?
Remote Method Invocation (RMI) allows java object that executes
on one machine and to invoke the method of a Java object to execute on another
machine. The steps involved in developing an RMI object are: a) Define the
interfaces b) Implementing these interfaces c) Compile the interfaces and their
implementations with the java compiler d) Compile the server implementation
with RMI compiler e) Run the RMI registry f) Run the application.
30. What is RMI architecture?
RMI architecture consists of four layers and each layer performs
specific functions: a) Application layer - contains the actual object
definition. b) Proxy layer - consists of stub and skeleton. c) Remote Reference
layer - gets the stream of bytes from the transport layer and sends it to the
proxy layer. d) Transportation layer - responsible for handling the actual
machine-to-machine communication.
31. What is a Java Bean?
A Java Bean is a software component that has been designed to be
reusable in a variety of different environments.
32. What are checked exceptions?
Checked exception are those which the Java compiler forces you
to catch. e.g. IOException are checked Exceptions.
33. What are runtime exceptions?
Runtime exceptions are those exceptions that are thrown at
runtime because of either wrong input data or because of wrong business logic
etc. These are not checked by the compiler at compile time.
34. What is the difference between error and an exception?
An error is an irrecoverable condition occurring at runtime. Such
as OutOfMemory error. These JVM errors and you can not repair them at runtime.
While exceptions are conditions that occur because of bad input etc. e.g.
FileNotFoundException will be thrown if the specified file does not exist. Or a
NullPointerException will take place if you try using a null reference. In most
of the cases it is possible to recover from an exception (probably by giving
user a feedback for entering proper values etc.).
35. What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the
opportunity to perform any cleanup processing before the object is garbage
collected. For example, closing a opened file, closing a opened database
Connection.
36. What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready
state. When a task invokes its sleep() method, it returns to the waiting state.
37. What is the difference between preemptive scheduling and time slicing?
Under preemptive scheduling, the highest priority task executes
until it enters the waiting or dead states or a higher priority task comes into
existence. Under time slicing, a task executes for a predefined slice of time
and then reenters the pool of ready tasks. The scheduler then determines which
task should execute next, based on priority and other factors.
38. What is mutable object and immutable object?
If a object value is changeable then we can call it as Mutable
object. (Ex., StringBuffer, …) If you are not allowed to change the value of an
object, it is immutable object. (Ex., String, Integer, Float, …)
39. What is the purpose of Void class?
The Void class is an uninstantiable placeholder class to hold a
reference to the Class object representing the primitive Java type void.
40. What is JIT and its use?
Really, just a very fast compiler… In this incarnation, pretty
much a one-pass compiler — no offline computations. So you can’t look at the
whole method, rank the expressions according to which ones are re-used the
most, and then generate code. In theory terms, it’s an on-line problem.
41. What is nested class?
If all the methods of a inner class is static then it is a
nested class.
42. What is HashMap and Map?
Map is Interface and Hashmap is class that implements that.
43. What are different types of access modifiers?
public: Any thing declared as public can be accessed from
anywhere. private: Any thing declared as private can’t be seen outside of its
class. protected: Any thing declared as protected can be accessed by classes in
the same package and subclasses in the other packages. default modifier : Can
be accessed only to classes in the same package.
44. What is the difference between Reader/Writer and InputStream/Output Stream?
The Reader/Writer class is character-oriented and the
InputStream/OutputStream class is byte-oriented.
45. What is servlet?
Servlets are modules that extend request/response-oriented
servers, such as java-enabled web servers. For example, a servlet might be
responsible for taking data in an HTML order-entry form and applying the
business logic used to update a company’s order database.
46. What is Constructor?
A constructor is a special method whose task is to initialize
the object of its class.
It is special because its name is the same as the class name.
They do not have return types, not even void and therefore they cannot return values.
They cannot be inherited, though a derived class can call the base class constructor.
Constructor is invoked whenever an object of its associated class is created.
It is special because its name is the same as the class name.
They do not have return types, not even void and therefore they cannot return values.
They cannot be inherited, though a derived class can call the base class constructor.
Constructor is invoked whenever an object of its associated class is created.
47. What is an Iterator ?
The Iterator interface is used to step through the elements of a Collection.
Iterators let you process each element of a Collection.
Iterators are a generic way to go through all the elements of a Collection no matter how it is organized.
Iterator is an Interface implemented a different way for every Collection.
48. What is the List interface?
The List interface provides support for ordered collections of
objects.
Lists may contain duplicate elements.
Lists may contain duplicate elements.
49. What is memory leak?
A memory leak is where an unreferenced object that will never be
used again still hangs around in memory and doesnt get garbage collected.
50. What is the difference between the prefix and postfix forms of the ++ operator?
The prefix form performs the increment operation and returns the
value of the increment operation. The postfix form returns the current value
all of the expression and then performs the increment operation on that value.
51. What is the difference between a constructor and a method?
A constructor is a member function of a class that is used to
create objects of that class. It has the same name as the class itself, has no
return type, and is invoked using the new operator.
A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator.
A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator.
52. What will happen to the Exception object after exception handling?
Exception object will be garbage collected.
53. Difference between static and dynamic class loading.
Static class loading: The process of loading a class using new
operator is called static class loading. Dynamic class loading: The process of
loading a class at runtime is called dynamic class loading.
Dynamic class loading can be done by using Class.forName(….).newInstance().
Dynamic class loading can be done by using Class.forName(….).newInstance().
54. Explain the Common use of EJB
The EJBs can be used to incorporate business logic in a
web-centric application.
The EJBs can be used to integrate business processes in Business-to-business (B2B) e-commerce applications.In Enterprise Application Integration applications, EJBs can be used to house processing and mapping between different applications.
The EJBs can be used to integrate business processes in Business-to-business (B2B) e-commerce applications.In Enterprise Application Integration applications, EJBs can be used to house processing and mapping between different applications.
55. What is JSP?
JSP is a technology that returns dynamic content to the Web
client using HTML, XML and JAVA elements. JSP page looks like a HTML page but
is a servlet. It contains Presentation logic and business logic of a web
application.
56. What is the purpose of apache tomcat?
Apache server is a standalone server that is used to test servlets
and create JSP pages. It is free and open source that is integrated in the
Apache web server. It is fast, reliable server to configure the applications
but it is hard to install. It is a servlet container that includes tools to
configure and manage the server to run the applications. It can also be
configured by editing XML configuration files.
57. Where pragma is used?
Pragma is used inside the servlets in the header with a certain
value. The value is of no-cache that tells that a servlets is acting as a proxy
and it has to forward request. Pragma directives allow the compiler to use
machine and operating system features while keeping the overall functionality
with the Java language. These are different for different compilers.
58. Briefly explain daemon thread.
Daemon thread is a low priority thread which runs in the
background performs garbage collection operation for the java runtime system.
59. What is a native method?
A native method is a method that is implemented in a language
other than Java.
60. Explain different way of using thread?
A Java thread could be implemented by using Runnable interface
or by extending the Thread class. The Runnable is more advantageous, when you
are going for multiple inheritance.
61. What are the two major components of JDBC?
One implementation interface for database manufacturers, the
other implementation interface for application and applet writers.
62. What kind of thread is the Garbage collector thread?
It is a daemon thread.
63. What are the different ways to handle exceptions?
There are two ways to handle exceptions,
1. By wrapping the desired code in a try block followed by a catch block to catch the exceptions. and
2. List the desired exceptions in the throws clause of the method and let the caller of the method handle those exceptions.
1. By wrapping the desired code in a try block followed by a catch block to catch the exceptions. and
2. List the desired exceptions in the throws clause of the method and let the caller of the method handle those exceptions.
64. How many objects are created in the following piece of code?
MyClass c1, c2, c3;
c1 = new MyClass ();
c3 = new MyClass ();
Answer: Only 2 objects are created, c1 and c3. The reference c2 is only declared and not initialized.
c1 = new MyClass ();
c3 = new MyClass ();
Answer: Only 2 objects are created, c1 and c3. The reference c2 is only declared and not initialized.
65.What is UNICODE?
Unicode
is used for internal representation of characters and strings and it uses 16
bits to represent each other.
DataStructure Questions:
1. Is it possible to find a loop in a Linked list ?
a. Possilbe at O(n)
b. Not possible
c. Possible at O(n^2) only
d. Depends on the position of loop
Solution: a. Possible at O(n)
Have two pointers say P1 and P2 pointing to the first node of the list.
Start a loop and Increment P1 once and P2 twice in each iteration. At any point of time if P1==P2 then there is a loop in that linked list. If P2 reaches NULL (end of linked list) then no loop exists.
a. Possilbe at O(n)
b. Not possible
c. Possible at O(n^2) only
d. Depends on the position of loop
Solution: a. Possible at O(n)
Have two pointers say P1 and P2 pointing to the first node of the list.
Start a loop and Increment P1 once and P2 twice in each iteration. At any point of time if P1==P2 then there is a loop in that linked list. If P2 reaches NULL (end of linked list) then no loop exists.
2. Two linked lists L1 and L2 intersects at a particular node N1 and from there all other nodes till the end are common. The length of the lists are not same. What are the possibilities to find N1?.
a. Solution exist for certain cases only
b. No linear solution exist
c. Linear solution is possible
d Only Non-linear solution exist.
Solution: c. Linear solution is possible
Have two pointers say P1 pointing to the first node of L1 and P2 to that of L2. Traverse through both the lists. If P1 reaches L1’s last node, point it to the first node of L2 and continue traversing. Do the same thing for P2 when it reaches L2’s last node. (By doing this, we are balancing the difference in the length between the linked lists. The shorter one will get over soon and by redirecting to longer list’s head, it will traverse the extra nodes also.) Finally they will Meet at the Intersection node.
b. No linear solution exist
c. Linear solution is possible
d Only Non-linear solution exist.
Solution: c. Linear solution is possible
Have two pointers say P1 pointing to the first node of L1 and P2 to that of L2. Traverse through both the lists. If P1 reaches L1’s last node, point it to the first node of L2 and continue traversing. Do the same thing for P2 when it reaches L2’s last node. (By doing this, we are balancing the difference in the length between the linked lists. The shorter one will get over soon and by redirecting to longer list’s head, it will traverse the extra nodes also.) Finally they will Meet at the Intersection node.
3. void PrintTree (Tree T)
{
if (T != NULL)
{
PrintTree (T-> Left);
PrintElement (T-> Element);
PrintTree (T->Right);
}
}
The above method ‘PrintTree’ results in which of the following traversal
a Inorder
b. Preorder
c. Postorder
d. None of the above
Solution: a. Inorder
Inorder:
void PrintTree (Tree T)
{
if (T != NULL)
{
PrintTree (T-> Left);
PrintElement (T-> Element);
PrintTree (T->Right);
}
}
For preorder use this order
PrintElement (T-> Element);
PrintTree (T-> Left);
PrintTree (T->Right);
For postorder use this order
PrintTree (T-> Left);
PrintTree (T->Right);
PrintElement (T-> Element);
{
if (T != NULL)
{
PrintTree (T-> Left);
PrintElement (T-> Element);
PrintTree (T->Right);
}
}
The above method ‘PrintTree’ results in which of the following traversal
a Inorder
b. Preorder
c. Postorder
d. None of the above
Solution: a. Inorder
Inorder:
void PrintTree (Tree T)
{
if (T != NULL)
{
PrintTree (T-> Left);
PrintElement (T-> Element);
PrintTree (T->Right);
}
}
For preorder use this order
PrintElement (T-> Element);
PrintTree (T-> Left);
PrintTree (T->Right);
For postorder use this order
PrintTree (T-> Left);
PrintTree (T->Right);
PrintElement (T-> Element);
4. Given a Binary Search Tree (BST), print its values in ascending order.
a. Perform Depth first traversal
b. Perform Breadth first traversal
c. Perform Postorder traversal
d. Perform Inorder traversal
Solution: d. Perform Inorder traversal
It is the properfy of BST and Inorder traversal.
b. Perform Breadth first traversal
c. Perform Postorder traversal
d. Perform Inorder traversal
Solution: d. Perform Inorder traversal
It is the properfy of BST and Inorder traversal.
5. Is it possible to implement a queue using Linked List ?. Enqueue & Dequeue should be O(1).
a. Not possible to implement.
b Only Enqueue is possible at O(1).
c. Only Dequeue is possible at O(1).
d. Both Enqueue and Dequeue is possible at O(1)
Solution: d. Both Enqueue and Dequeue is possible at O(1)
Have two pointers H pointing to the Head and T pointing to the Tail of the linked list. Perform enqueue at T and perform dequeue at H. Update the pointers after each operations accordingly.
b Only Enqueue is possible at O(1).
c. Only Dequeue is possible at O(1).
d. Both Enqueue and Dequeue is possible at O(1)
Solution: d. Both Enqueue and Dequeue is possible at O(1)
Have two pointers H pointing to the Head and T pointing to the Tail of the linked list. Perform enqueue at T and perform dequeue at H. Update the pointers after each operations accordingly.
6. Given a Tree, is it possible to find the greatest and least among leaves in linear time?.
a. Solution depends on the tree structure
b.Linear solution exist
c. Only Non-linear solution exist.
d. No linear solution exist
Solution: b. Linear solution exist
Have two variables Min and Max. Perform any tree traversal.Assign the first traversed leaf element to Min and Max for all other leaf elements check with these variables and update it accordingly. If a current element is < Min then update Min with that element. If it is > Min then check with Max.
Note: If you want to find the greatest and least among all nodes perform the checks for each node traversed.
b.Linear solution exist
c. Only Non-linear solution exist.
d. No linear solution exist
Solution: b. Linear solution exist
Have two variables Min and Max. Perform any tree traversal.Assign the first traversed leaf element to Min and Max for all other leaf elements check with these variables and update it accordingly. If a current element is < Min then update Min with that element. If it is > Min then check with Max.
Note: If you want to find the greatest and least among all nodes perform the checks for each node traversed.
7. Is it possible to find find the greatest and least value among the nodes in a given BST without using any extra variables?
a. No solution exist.
b. Solution need 2 extra variables
c. Solution exist without any extra variables
d Solution need 1 extra variable
Solution:c Solution exist without any extra variables
As per BST property, the left most node should be the least one and the rightmost node should be the greatest. In other words, the first and last node of an Inorder traversal are the least and greatest among the nodes respectively.
b. Solution need 2 extra variables
c. Solution exist without any extra variables
d Solution need 1 extra variable
Solution:c Solution exist without any extra variables
As per BST property, the left most node should be the least one and the rightmost node should be the greatest. In other words, the first and last node of an Inorder traversal are the least and greatest among the nodes respectively.
8. Is it possible to implement 2 stack in an array?
Condition: None of the stack should indicate an overflow until
every slot of an array is used.
a. Only 1 stack can be implemented for the given condition
b. Stacks can not be implemented in array
c. 2 stacks can be implemented for the given condition.
d. 2 stacks can be implemented if the given condition is applied only for 1 stack.
Solution:c. 2 stacks can be implemented for the given condition
Start 1st stack from left (1st position of an array) and 2nd from right (last position say n). Move 1st stack towards right( i.e 1,2,3 ...n) and 2nd towards left (i.e n,n-1,n-2...1).
a. Only 1 stack can be implemented for the given condition
b. Stacks can not be implemented in array
c. 2 stacks can be implemented for the given condition.
d. 2 stacks can be implemented if the given condition is applied only for 1 stack.
Solution:c. 2 stacks can be implemented for the given condition
Start 1st stack from left (1st position of an array) and 2nd from right (last position say n). Move 1st stack towards right( i.e 1,2,3 ...n) and 2nd towards left (i.e n,n-1,n-2...1).
9. Given two keys K1 & K2, write an algorithm to print all the elements between them with K1<=K2 in a BST.
a. Solution need 2 extra spaces
b. Linear solution is possible without using any extra space
c No linear solution exist
d Solution need 1 extra space
Solution:b. Linear solution is possible without using any extra space
Perform an inorder traversal. Once you find K1 print it and continue traversal now, print all other traversed elements until you reach K2.
Note: If K1 == K2 stop once you find K1.
b. Linear solution is possible without using any extra space
c No linear solution exist
d Solution need 1 extra space
Solution:b. Linear solution is possible without using any extra space
Perform an inorder traversal. Once you find K1 print it and continue traversal now, print all other traversed elements until you reach K2.
Note: If K1 == K2 stop once you find K1.
10. How many stacks are required to implement a Queue.
a. One
b. Two
c. Three
d. Two + one extra space.
Solution:b Two
Have two stacks S1 and S2.
For Enqueue, perform push on S1.
For Dequeue, if S2 is empty pop all the elements from S1 and push it to S2. The last element you popped from S1 is an element to be dequeued. If S2 is not empty, then pop the top element in it.
b. Two
c. Three
d. Two + one extra space.
Solution:b Two
Have two stacks S1 and S2.
For Enqueue, perform push on S1.
For Dequeue, if S2 is empty pop all the elements from S1 and push it to S2. The last element you popped from S1 is an element to be dequeued. If S2 is not empty, then pop the top element in it.
Operating
Systems Questions:
1. What is an operating system?
An operating system is a program that acts as an intermediary
between the user and the computer hardware. The purpose of an OS is to provide
a convenient environment in which user can execute programs in a convenient and
efficient manner.
2. What are the different operating systems?
1. Batched operating systems
2. Multi-programmed operating systems
3. timesharing operating systems
4. Distributed operating systems
5. Real-time operating systems
3. What are the basic functions of an operating system?
Operating system controls and coordinates the use of the
hardware among the various applications programs for various uses. Operating
system acts as resource allocator and manager. Also operating system is control
program which controls the user programs to prevent errors and improper use of
the computer. It is especially concerned with the operation and control of I/O
devices.
4. What is kernel?
Kernel is the core and essential part of computer operating
system that provides basic services for all parts of OS.
5. What is difference between micro kernel and macro kernel?
Micro kernel is a kernel which run services those are minimal
for operating system performance. In this kernel all other operations are
performed by processor.
Macro Kernel is a combination of micro and monolithic kernel. In
monolithic kernel all operating system code is in single executable image.
6. What is dead lock?
Deadlock is a situation or condition where the two processes are
waiting for each other to complete so that they can start. This result both the
processes to hang.
7. What is a process?
A program in execution is called a process.
Processes are of two types:
1. Operating system processes
2. User processes
1. Operating system processes
2. User processes
8. What are the states of a process?
1. New
2. Running
3. Waiting
4. Ready
5. Terminated
2. Running
3. Waiting
4. Ready
5. Terminated
9. What is starvation and aging?
Starvation is Resource management problem where a process does
not get the resources it needs for a long time because the resources are being
allocated to other processes.
Aging is a technique to avoid starvation in a scheduling system.
10. What is semaphore?
Semaphore is a variable, whose status reports common resource,
Semaphore is of two types one is Binary semaphore and other is Counting
semaphore.
11. What is context switching?
Transferring the control from one process to other process
requires saving the state of the old process and loading the saved state for
new process. This task is known as context switching.
12. What is a thread?
A thread is a program line under execution. Thread sometimes
called a light-weight process, is a basic unit of CPU utilization; it comprises
a thread id, a program counter, a register set, and a stack
13. What is process synchronization?
A situation, where several processes access and manipulate the
same data concurrently and the outcome of the execution depends on the
particular order in which the access takes place, is called race condition. To
guard against the race condition we need to ensure that only one process at a
time can be manipulating the same data. The technique we use for this is called
process synchronization.
14. What is virtual memory?
Virtual memory is hardware technique where the system appears to
have more memory that it actually does. This is done by time-sharing, the
physical memory and storage parts of the memory one disk when they are not
actively being used.
15. What is thrashing?
It is a phenomenon in virtual memory schemes when the processor
spends most of its time swapping pages, rather than executing instructions.
This is due to an inordinate number of page faults.
16. What is fragmentation? Tell about different types of
fragmentation?
When many of free blocks are too small to satisfy any request
then fragmentation occurs. External fragmentation and internal fragmentation
are two types of fragmentation. External Fragmentation happens when a dynamic
memory allocation algorithm allocates some memory and a small piece is left
over that cannot be effectively used. Internal fragmentation is the space
wasted inside of allocated memory blocks because of restriction on the allowed
sizes of allocated blocks.
17. What are necessary conditions for dead lock?
1. Mutual exclusion (where at least one resource is
non-sharable)
2. Hold and wait (where a process holds one resource and waits
for other resource)
3. No preemption (where the resources can’t be preempted)
4. Circular wait (where p[i] is waiting for p[j] to release a
resource. i= 1,2,…n
j=if (i!=n) then i+1
else 1 )
18. What is cache memory?
Cache memory is random access memory (RAM) that a computer
microprocessor can access more quickly than it can access regular RAM. As the
microprocessor processes data, it looks first in the cache memory and if it
finds the data there (from a previous reading of data), it does not have to do
the more time-consuming reading of data from larger memory.
19. What is logical and physical addresses space?
Logical address space is generated from CPU; it bound to a
separate physical address space is central to proper memory management.
Physical address space is seen by the memory unit. Logical address space is
virtual address space. Both these address space will be same at compile time
but differ at execution time.
20. Differentiate between Complier and Interpreter?
An interpreter reads one instruction at a time and carries out
the actions implied by that instruction. It does not perform any translation.
But a compiler translates the entire instructions
21. What is Throughput, Turnaround time, waiting time and
Response time?
Throughput – number of processes that complete their execution
per time unit
Turnaround time – amount of time to execute a particular process
Waiting time – amount of time a process has been waiting in the
ready queue
Response time – amount of time it takes from when a request was
submitted until the first response is produced, not output (for time-sharing
environment)
22. What is Memory-Management Unit (MMU)?
Hardware device that maps virtual to physical address. In MMU
scheme, the value in the relocation register is added to every address
generated by a user process at the time it is sent to memory.
->The user program deals with logical addresses; it never
sees the real physical addresses
23. What is a Real-Time System?
A real time process is a process that must respond to the events
within a certain time period. A real time operating system is an operating
system that can run real time processes successfully
24. What is a trap and trapdoor?
Trapdoor is a secret undocumented entry point into a program
used to grant access without normal methods of access authentication. A trap is
a software interrupt, usually the result of an error condition.
25. When is a system in safe state?
The set of dispatchable processes is in a safe state if there
exists at least one temporal order in which all processes can be run to
completion without resulting in a deadlock.
26. Explain the concept of the Distributed systems?
Distributed systems work in a network. They can share the
network resources, communicate with each other.
27. What is cache-coherency?
In a multiprocessor system there exist several caches each may
containing a copy of same variable A. Then a change in one cache should
immediately be reflected in all other caches this process of maintaining the
same value of a data in all the caches s called cache-coherency.
28. What is a long term scheduler & short term schedulers?
Long term schedulers are the job schedulers that select
processes from the job queue and load them into memory for execution. The short
term schedulers are the CPU schedulers that select a process from the ready
queue and allocate the CPU to one of them.
29. Explain the meaning of mutex.
Mutex is the short form for ‘Mutual Exclusion object’. A mutex
allows multiple threads for sharing the same resource. The resource can be
file. A mutex with a unique name is created at the time of starting a program.
A mutex must be locked from other threads, when any thread that needs the
resource. When the data is no longer used / needed, the mutex is set to unlock.
30. What is cycle stealing?
We encounter cycle stealing in the context of Direct Memory
Access (DMA). Either the DMA controller can use the data bus when the CPU does
not need it, or it may force the CPU to temporarily suspend operation. The
latter technique is called cycle stealing. Note that cycle stealing can be done
only at specific break points in an instruction cycle.
31. What is Marshalling?
The process of packaging and sending interface method parameters
across thread or process boundaries.
32. What is a daemon?
Daemon is a program that runs in the background without user’s
interaction. A daemon runs in a multitasking operating system like UNIX. A
daemon is initiated and controlled by special programs known as ‘processes’.
33. What is pre-emptive and non-preemptive scheduling?
Preemptive scheduling: The preemptive scheduling is prioritized.
The highest priority process should always be the process that is currently
utilized.
Non-Preemptive scheduling: When a process enters the state of
running, the state of that process is not deleted from the scheduler until it
finishes its service time.
34. What is busy waiting?
The repeated execution of a loop of code while waiting for an
event to occur is called busy-waiting. The CPU is not engaged in any real
productive activity during this period, and the process does not progress
toward completion.
35. What is page cannibalizing?
Page swapping or page replacements are called page
cannibalizing.
36. What is SMP?
To achieve maximum efficiency and reliability a mode of
operation known as symmetric multiprocessing is used. In essence, with SMP any
process or threads can be assigned to any processor.
37. What is process migration?
It is the transfer of sufficient amount of the state of process
from one machine to the target machine.
38. Difference between Primary storage and secondary storage?
Primary memory is the main memory (Hard disk, RAM) where the
operating system resides.
Secondary memory can be external devices like CD, floppy
magnetic discs etc. secondary storage cannot be directly accessed by the CPU
and is also external memory storage.
39. Define compactions.
Compaction is a process in which the free space is collected in
a large memory chunk to make some space available for processes.
40. What are residence monitors?
Early operating systems were called residence monitors.
41. What is dual-mode operation?
In order to protect the operating systems and the system
programs from the malfunctioning programs the two mode operations were evolved
System mode
User mode.
System mode
User mode.
42. What is a device queue?
A list of processes waiting for a particular I/O device is
called device queue.
43. What are the different types of Real-Time Scheduling?
Hard real-time systems required to complete a critical task
within a guaranteed amount of time.
Soft real-time computing requires that critical processes receive priority over less fortunate ones.
Soft real-time computing requires that critical processes receive priority over less fortunate ones.
44. What is relative path and absolute path?
Absolute path-- Exact path from root directory.
Relative path-- Relative to the current path.
Relative path-- Relative to the current path.
45. What are the disadvantages of context switching?
Time taken for switching from one process to other is pure over
head. Because the system does no useful work while switching. So one of the
solutions is to go for threading when ever possible.
46. What is a data register and address register?
Data registers - can be assigned to a variety of functions by
the programmer. They can be used with any machine instruction that performs
operations on data.
Address registers - contain main memory addresses of data and instructions or they contain a portion of the address that is used in the calculation of the complete addresses.
Address registers - contain main memory addresses of data and instructions or they contain a portion of the address that is used in the calculation of the complete addresses.
47. What is DRAM?
Dynamic Ram stores the data in the form of Capacitance, and
Static RAM stores the data in Voltages.
48. What are local and global page replacements?
Local replacement means that an incoming page is brought in only
to the relevant process' address space. Global replacement policy allows any
page frame from any process to be replaced. The latter is applicable to
variable partitions model only.
49. Explain the concept of the batched operating systems?
In batched operating system the users gives their jobs to the
operator who sorts the programs according to their requirements and executes
them. This is time consuming but makes the CPU busy all the time.
50. What is SCSI?
SCSI - Small computer systems interface is a type of interface
used for computer components such as hard drives, optical drives, scanners and
tape drives. It is a competing technology to standard IDE (Integrated Drive
Electronics).
51.When is a system in safe state?
The set of dispatchable processes is in a safe state if there
exists at least one temporal order in which all processes can be run to
completion without resulting in a deadlock.
52. What is cycle stealing?
We encounter cycle stealing in the context of Direct Memory
Access (DMA). Either the DMA controller can use the data bus when the CPU does
not need it, or it may force the CPU to temporarily suspend operation. The
latter technique is called cycle stealing. Note that cycle stealing can be done
only at specific break points in an instruction cycle.
53. What is an idle thread?
The special thread a dispatcher will execute when no ready
thread is found.
54. What is FtDisk?
It is a fault tolerance disk driver for Windows NT.
55.What is Dispatcher?
Dispatcher module gives control of the CPU to the process
selected by the short-term scheduler; this involves: Switching context,
Switching to user mode, Jumping to the proper location in the user program to
restart that program, dispatch latency – time it takes for the dispatcher to
stop one process and start another running.
56. When does the condition 'rendezvous' arise?
In message passing, it is the condition in which, both, the
sender and receiver are blocked until the message is delivered.
57. What is process spawning?
When the OS at the explicit request of another process creates a
process, this action is called process spawning
58. What are the reasons for process suspension?
1) swapping
2) interactive user request
3) timing
4) parent process request
1) swapping
2) interactive user request
3) timing
4) parent process request
59. What are the sub-components of I/O manager in Windows NT?
1) Network redirector/ Server
2) Cache manager.
3) File systems
4) Network driver
5) Device driver
1) Network redirector/ Server
2) Cache manager.
3) File systems
4) Network driver
5) Device driver
60. What is a drawback of MVT?
1) ability to support multiple processors
2) virtual storage
3) source level debugging
1) ability to support multiple processors
2) virtual storage
3) source level debugging
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