SD - Stack

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

#define MAX_STACK 100

typedef int infotype;

typedef struct{
    infotype top;
    int content[MAX_STACK];
}Stack;

void init(Stack *S)
{
    (*S).top=-1;
}

void push(Stack *S, int value)
{
    if((*S).top < (MAX_STACK - 1))
    {
        (*S).top++;
        (*S).content[(*S).top] = value;
    }
    else
        printf("\nStack penuh...");
}

infotype pop(Stack *S)
{
    infotype a;

    if ((*S).top > -1)
    {
        a=(*S).content[(*S).top];
        (*S).top--;
        return(a);
    }
    else
    {
        printf("\nStack kosong...");
        return 0;
    }
}

void show(Stack S)
{
    if (S.top > -1)
    {
        while (S.top != -1)
        {
            printf("\n %d", S.content[S.top]);
            S.top--;
        }
    }
    else
        printf("\nStack kosong...");
}

void randomContent(Stack *S, int n)
{
    int x;
    if((*S).top < (MAX_STACK - 1))
    {
        (*S).top=n;
        (*S).top++;
        x=rand()%100;
        (*S).content[(*S).top] = x;
    }
    else
        printf("\nStack penuh...");
}

void main()
{
    Stack myStack;
    char pilih;
    infotype newVal,maks,a;
    init(&myStack);
    do
    {
        system("cls");
        printf("\n++++++ MENU ++++++");
        printf("\n1. PUSH");
        printf("\n2. POP");
        printf("\n3. ShowAll");
        printf("\n4. PUSH yg diacak");
        printf("\n\nPilihan : ");
        pilih = getch();

        switch(pilih)
        {
        case '1' :
            printf("\nMasukkan nilai yang akan di-Push : ");
            scanf("%d",&newVal);
            push(&myStack, newVal);
            getch();
            break;
        case '2' :
            a=pop(&myStack);
            printf("\nIsi stack yang di-POP : %d",a);
            getch();
            break;
        case '3' :
            show(myStack);
            getch();
            break;
        case '4' :
            printf("\nMasukkan maksimal bilangan : ");
            scanf("%d",&maks);
            randomContent(&myStack,maks);
            getch();
            break;
        }
    }while(pilih != 27);
}