Stack using linked list

/*

Write a program of stack using linked list

*/

#include<stdio.h>
#include<stdlib.h>

struct node

{

int info;

struct node *link;

}*top=NULL;

void push(int item);

int pop();

int peek();

int isEmpty();

void display();

main()

{

int choice,item;

while(1)

{

printf("1.Push\n");

printf("2.Pop\n");

printf("3.Display item at the top\n");

printf("4.Display all items of the stack\n");

printf("5.Quit\n");

printf("Enter your choice : ") ;

scanf("%d", &choice);

switch(choice)

{

case 1:

printf("Enter the item to be pushed : ");

scanf("%d",&item);

push(item);

break;

case 2:

item=pop();

printf("Popped item is : %d\n",item);

break;

case 3:

printf("Item at the top is %d\n",peek());

break;

case 4:

display();

break;

case 5:

exit(1);

default :

printf("Wrong choice\n");

}
}
}

void push(int item)

{

struct node *tmp;

tmp=(struct node *)malloc(sizeof(struct node));

if(tmp==NULL)

{

printf("Stack Overflow\n");

return;

}

tmp->info=item;

tmp->link=top;

top=tmp;

}

int pop()

{

struct node *tmp;

int item;

if( isEmpty() )

{

printf("Stack Underflow\n");

exit(1);

}

tmp=top;

item=tmp->info;

top=top->link;

free(tmp);

return item;

}

int peek()

{

if( isEmpty() )

{

printf("Stack Underflow\n");

exit(1);

}

return top->info;

}

int isEmpty()

{

if(top == NULL)

return 1;

else

return 0;

}

void display()

{

struct node *ptr;

ptr=top;

if(isEmpty())

{

printf("Stack is empty\n");

return;

}

printf("Stack elements :\n\n");

while(ptr!=NULL)

{

printf(" %d\n",ptr->info);

ptr=ptr->link;

}

printf("\n");

}