Implementation Of Stack Operation (Static) Using Structure – Data Structures in C Program

#include<stdio.h>
#include<stdlib.h>

#define CAPACITY 5

struct stack {
    int data[CAPACITY];
    int tos;
};

typedef struct stack * STACK;

void print(STACK x){
    printf("S>> \n");
    for(int i = x->tos; i>=0; i--)
        printf("%d\n", x->data[i]);
}

STACK push(STACK x, int item){
    if(x->tos == CAPACITY -1 ){
        printf("S FULL (OVERFLOW)\n");
        return x;
    }

    x->data[++x->tos] = item;
    return x;
}

STACK peek(STACK x){
    if(x->tos == -1) {
        printf("S has no elements\n");
        return x;
    }

    printf("TOP OF S >> %d\n", x->data[x->tos]);
    return x;
}

STACK pop(STACK x){
    if(x->tos == -1){
        printf("S EMPTY (UNDERFLOW)\n");
        return x;
    }

    printf("POPPED ELEMENT >> %d\n", x->data[x->tos--]);
    return x;
}

void main(){
    struct stack S;
    STACK s = &S;
    s->tos = -1;
    int item, choice;

    for(;;){
        printf("!!!___   S   ___!!!\n1. PUSH \n2. PEEK\n3. POP\n4. PRINT\n");
        printf("Enter choice>> ");
        scanf("%d", &choice);

        switch (choice){
            case 1:
                printf("Enter Element for Push operation>> ");
                scanf("%d", &item);
                s = push(s, item);
                print(s);
                break;
            
            case 2:
                s = peek(s);
                break;

            case 3:
                s = pop(s);
                print(s);
                break;

            case 4:
                print(s);
                break;

            default:
                exit(0);
        }
    }
}