一个自己实现的栈，如有缺陷请指出

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

int push(char* stack, int top, char elem) {
    stack[++top] = elem;

    printf("入栈元素：%c\n", elem);

    return top;
}

int pop(char* stack, int top) {
    if(top == -1) {
        return -1;
    }

    printf("出栈元素：%c\n", stack[top]);
    top--;

    return top;
}

int main()
{
    char c[10];
    int top = -1;

    top = push(c, top, 'A');
    top = push(c, top, 'B');
    top = push(c, top, 'C');
    top = push(c, top, 'D');
    top = push(c, top, 'E');

    top = pop(c, top);
    top = pop(c, top);
    top = pop(c, top);
    top = pop(c, top);
    top = pop(c, top);
    return 0;
}