Stack implementation( Push, Pop, Display) in C programming.

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#define size 5

struct stack {
    int s[size];
    int top;
    } st;

int stfull()
{
    if (st.top>= size -1)
        return 1;
    else
        return 0;
}
push(int item)
{
    st.top++;
    st.s[st.top] = item;
}
int stempty()
{
    if (st.top== -1)
    return 1;
    else
    return 0;
}
int pop()
{
    int item;
    item = st.s[st.top];
    st.top--;
    return (item);
}

display()
{
    int i;
    if (stempty())
    printf("\nStack Is Empty!");
    else {
    for (i= st.top; i>= 0; i--)
    printf("\n%d", st.s[i]);
    }
}
int main()
{
    int item, choice;
    char ans;
    st.top= -1;

    printf("\n\tImplementation Of Stack\n");
    do {
        printf("\nMain Menu");
        printf("\n1.Push \n2.Pop \n3.Display \n4.exit");
        printf("\nEnter Your Choice ");
        scanf("%d", &choice);
    switch (choice) {
    case 1:
        printf("\nEnter The item to be pushed   ");
        scanf("%d", &item);
        if (stfull())
            printf("\nStack is Full!");
        else
            push(item);
        break;

    case 2:
        if (stempty())
            printf("\nEmpty stack! Underflow!!");
        else {
            item = pop();
            printf("\nThe popped element is %d", item);
        }
        break;

    case 3:
        display();
        break;
    case 4:
        exit(0);
    }
    printf("\nDo You want To Continue?  ");
    ans= getche();
    }
    while (ans == 'Y' || ans == 'y');
    return 0;
}

Output:

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