18.stack_using_array.c

#include <stdio.h>

int stack[100], n=100, top;

int push(int data) 
{
	if (top >= n-1)
  {
		printf("Stack overflow\n");
		return 0;
	} 
  else
  {
		stack[++top] = data;
		return 1;
	}
}
int pop()
{
	if (top == -1)
  {
		printf("Stack underflow\n");
		return 0;
    }
  else 
  {
		printf("Popped element is %d\n", stack[top]);
		top--;
		return 1;
	}
}
int display()
{
	int i;
	printf("\n\nStack contents\n");
	if (top == -1)
  {
		printf("Empty stack\n");
	} else {
		for (i=top; i>=0; i--) 
    {
			printf("%d\n", stack[i]);
		}
	}
	printf("\n");
}
int main()
{
	top = -1;
	char ans;
	int data;
	do
  {
		printf("\n\n\tStack Using array\n");
		printf("1. Push\n2. Pop\n3. Display\n4. Exit\nEnter your choice : ");
		scanf(" %c", &ans);
		switch (ans)
    {
			case '1':
				printf("Enter data to be pushed : ");
				scanf(" %d", &data);
				push(data);
				break;
			case '2':
				pop();
				break;
			case '3':
				display();
				break;
			default:
				printf("Invalid choice.\n");
		}
	} while (ans != '4');
}