Description:
In
this program we have to implement the stack operation by using the pointers.
Here they stack operation are push and pop. Push operation is used to insert
the elements into a stack and pop operation is used to remove the elements in
to a stack.
#include<stdio.h>
#include<conio.h>
//typedef struct stack
struct stack_tag
{
int *s;
int top,size;
};
typedef struct stack_tag stack;
stack init();
void push();
int pop();
void display(stack a);
void menu()
{
printf("1. insertion\n");
printf("2. deletion\n");
printf("3.display stack\n");
printf("4.exit\n");
}
stack init()
{
stack a;
printf("enter size of the stack\n");
scanf("%d",&a.size);
a.top=-1;
a.s=(int*)malloc(a.size*sizeof(int));
return(a);
}
//b=init();
//push()
void push(stack *p,int x)
{
if(p->top==p->size-1)
{
printf("stack is full, insertion is not possible\n");
}
else
{
p->top++;
p->s[p->top]=x;
}
}
//pop()
int pop(stack *p)
{
int x;
if(p->top==-1)//is stack empty?
return(-1);
else{
x=p->s[p->top];//store top most value in x
p->top--;
return(x);
}
}
//x=pop(&a);
void display(stack a)
{
int i;
if(a.top==-1)
{
printf("stack is empty\n");
}
else
{
printf("stack is as follows\n");
for(i=a.top;i>=0;i--)//display values in the stack in reverse order
{ //since stak is LIFO
printf("%d\n",a.s[i]);
}
}//end of else
}
int topmost(stack a)
{
if(a.top==-1)
return(-1);
else
return(a.s[a.top]);
}
//x=topmost(a);
void main()
{
stack a;
int ch,x;
clrscr();
a=init();//initialize members of tht structures s,top,size
clrscr();
printf("enter your choice\n");
scanf("%d",&ch);
while(ch<5)//execute loop until uses,entered choice is 5
{
switch(ch)
{
case 1:{
printf("enter value to be inserted\n");
scanf("%d",&x);
break;
}
case 2:{
x=pop(&a);//delete top most value in the stack
if(x==-1)
printf("stack is empty, del not posible\n");
else
printf("deleted value is %d\n",x);
break;
}
case 3:{
display(a);//disp value in the stack in rever order
break;
}
case 4: {
x=topmost(a);
if(x==-1)
printf("stack is empty\n");
else
printf("top most value is %d\n",x);
break;
}
}//switch
menu();
printf("enter ur choice\n");
scanf("%d",&ch);
}//while
getch();
}
