Stack using array

C Program

#include
#include 
#define MAX 50
int size;

typedef struct stack
{
int data[MAX];
int top;
}stack;

void init(stack *s)
{
 s->top = -1;
}

int empty(stack *s)
{
if(s->top==-1)
 return(1);
else
 return(0);
}

int full(stack *s)
{
 if(s->top==size-1)
  return(1);
 else
  return(0);
}

void push(stack *s, int x)
{
 s->top++;
 s->data[s->top] = x;
}

int pop(stack *s)
{
   int x;

   x = s->data[s->top];
   s->top--;
   return(x);
}

void display(stack *s)
{
   int i;
   for (i = s->top; i >= 0; i--)
   printf("\n%d", s->data[i]);
}

int main()
{
int ch,val;
stack s;
init(&s);

printf("Enter Stack Size :");
scanf("%d", &size);

do
{
printf("\nSTACK PRIMITIVE OPERATIONS");
printf("\n1.PUSH"); printf("\n2.POP");
printf("\n3.DISPLAY"); printf("\n4.QUIT");
printf("\nEnter your option : ");  scanf("%d", &ch);

switch(ch)
{
	
case 1: 
if(full(&s))
{
printf("Sorry STACK is Full(i.e.'STACK OVERFLOW')....");
}
else
{
printf("\nEnter the element into stack:");
scanf("%d", &val);
push(&s, val);
}
break;

case 2:
if(empty(&s))
{
printf("Sorry STACK is Empty(i.e.'STACK UNDERFLOW')....");
}
else
{
val = pop(&s);
printf("\nThe element popped from stack is : %d",val);
}
break;

case 3:
if(empty(&s))
{
printf("Sorry their is no any element in the STACK.....");
}
else
{
printf("\nThe current stack elements are:");
display(&s);
}
break;

case 4:exit(0);
default: printf("\nEnter correct option!Try again.");
}

}while(1);

 return 0;
}

Output:

Enter Stack Size :3

STACK PRIMITIVE OPERATIONS
1.PUSH
2.POP
3.DISPLAY
4.QUIT
Enter your option : 1

Enter the element into stack:20

STACK PRIMITIVE OPERATIONS
1.PUSH
2.POP
3.DISPLAY
4.QUIT
Enter your option : 1

Enter the element into stack:30

STACK PRIMITIVE OPERATIONS
1.PUSH
2.POP
3.DISPLAY
4.QUIT
Enter your option : 3

The current stack elements are:
30
20

Enter the element into stack:30

STACK PRIMITIVE OPERATIONS
1.PUSH
2.POP
3.DISPLAY
4.QUIT
Enter your option : 2

The element popped from stack is : 30

STACK PRIMITIVE OPERATIONS
1.PUSH
2.POP
3.DISPLAY
4.QUIT
Enter your option : 2

The element popped from stack is : 20

STACK PRIMITIVE OPERATIONS
1.PUSH
2.POP
3.DISPLAY
4.QUIT
Enter your option : 4