#include<stdio.h>
#include<stdlib.h>
typedef struct {
int key;
} element;
struct stack {
element data;
struct stack *link;
};
typedef struct stack *stckptr;
stckptr top = NULL;
void push(element item) {
stckptr temp;
temp = (stckptr)malloc(sizeof(struct stack));
temp->data = item;
temp->link = top;
top = temp;
}
element pop() {
stckptr temp;
element item;
if (top == NULL) {
item.key = -1;
return item;
}
else {
temp = top;
top = top->link;
item = temp->data;
free(temp);
return item;
}
}
void display() {
stckptr temp = top;
while (temp != NULL) {
printf("%d\t", temp->data.key);
temp = temp->link;
}
}
int main() {
element item;
int choice;
while (1) {
printf("\nEnter\n1. Push\n2. Pop\n3. Display\n4. Exit\n");
scanf("%d", &choice);
switch (choice) {
case 1:
printf("\nEnter element to push: ");
scanf("%d", &item.key);
push(item);
break;
case 2:
item = pop();
if (item.key == -1)
printf("\nStack Underflow!\n");
else
printf("\nPopped element: %d\n", item.key);
break;
case 3:
printf("\nStack: ");
display();
break;
case 4:
exit(0);
default:
printf("\nInvalid choice!\n");
}
}
return 0;
}