栈的实现（C语言）

#include<stdio.h>
#include<stdlib.h>
#define Maxsize 100
typedef int datetype;
typedef struct{
    datetype a[Maxsize];
    int top;
}sequence_stack;
void init(sequence_stack* st)
{
    st->top=0;
}
int empty(sequence_stack st)
{
    return (st.top?0:1);
}
datetype read(sequence_stack st)
{
    if(empty(st))
    {
        printf("栈是空的！\n");
        exit(1);
    }
    else
    return st.a[st.top-1];
}
void push(sequence_stack *st)
{
    if(st->top==Maxsize)
    {
        printf("The sequence stack is full!\n");
        exit(1);
    }
    datetype x;
    printf("请输入你想要添加到栈里的数据，以0为结束符:\n");
    scanf("%d",&x);
    while(x&&st->top<Maxsize)
    {
        st->a[st->top++]=x;
        scanf("%d",&x);
    }
}
void pop(sequence_stack *st)
{
    if(!st->top)
    {
        printf("The sequence stack if empty!\n");
        exit(1);
    }
    else
        st->top--;
}
int main()
{
    sequence_stack st;
    init(&st);
    push(&st);
    datetype a;
    while(st.top)
    {
        a=read(st);
        printf("%-5d",a);
        pop(&st);
    }
    return 0;
}