1.Stack using array (DS)

#include<stdio.h>
#include<conio.h>
#define max 100
typedef struct
{
    int s[max];
    int tos;
}stack;
int isempty(stack *t)
{
    if(t->tos==-1)
        return 1;
    else return 0;
}
void push(stack *t,int ele)
{
    if(t->tos==(max-1))
    {
        printf("\n STACK OVERFLOW");
        return;
    }
    else
    {
        t->tos=t->tos+1;
        t->s[t->tos]=ele;
        return;
    }
}
void pop(stack *t)
{
    int z;
    if(isempty(t)==1)
    {
        printf("\nSTACK UNDERFLOW");
        return;
    }
    else
    {
        z = t->s[t->tos];
        t->tos = t->tos-1;
        printf("\nDeleted element is %d",z);
        return;
    }
}
void top(stack *t)
{
    int z;
    if(isempty(t)==1)
    {
        printf("\nSTACK UNDERFLOW");
        return;
    }
    else
    {
        z = t->s[t->tos];
        printf("\nTOP of stack is %d",z);
        return;
    }
}
void display(stack *t)
{
    int i;
    if(isempty(t)==1)
    {
        printf("\nSTACK UNDERFLOW");
        return;
    }
    else
    {
        printf("\nELEMENTS OF STACK is given below\n");
        for(i=tos;i>=0;i--)
        {
            printf("%d\t",t->s[i]);
        }
        return ;
    }
}
int main()
{
    int ch,ele;
    stack x;
    x.tos = -1;
    printf("IMPELEMENTATION of STACK USING ARRAY\n");
    while(1)
    {
        printf("\n1.INSERT ELEMENT IN STACK \n2.DELETE ELEMENT FROM STACK \n3.TOP OF STACK \n4.DISPLAY ELEMENTS OF STACK \n5.EXIT\n");
        scanf_s("%d",&ch);
        if(ch==5)
            break;
        else
        {
            switch(ch)
            {
            case 1: printf("\n enter element to insert in stack");
                    scanf_s("%d",&ele);
                    push(&x,ele);
                    break;
            case 2:pop(&x);
                    break;
            case 3:top(&x);
                    break;
            case 4:display(&x);
                    break;
            default:printf(" Invalid input");
            }
        }
    }
    _getch();
    return 0;
}