利用栈对两个数据存储并进行操作+-*/运算

#include <stdio.h>
#include <stdlib.h>
#define Max 100

int *p;
int *tos;
int *bos;

/*添加一个数据放到堆栈对顶端*/
void push(int i)
{
    if (p > bos)
    {
        printf("堆栈以满
");
        return;
    }
    *p = i;
    p++;
}

/*丛堆栈顶端取出一个数据*/
int pop(void)
{
    p--;
    if (p < tos)
    {
        printf("堆栈下溢
");
        return 0;
    }
    return *p;
}

int main()
{
    int a, b;
    char s[80];
    p = (int *)malloc(Max*sizeof(int));
    if (!p)
    {
        printf("分配内存失败");
        exit(1);
    }
    tos = p;
    bos = p + Max - 1;
    printf("请输入第一个数据:
");
    scanf("%d", &a);
    push(a);
    printf("请输入第二个数据:
");
    scanf("%d", &b);
    push(b);
    printf("请输入操作符:
");
    scanf("%s", s);
    switch (*s)
    {
    case '+':
        a = pop();
        b = pop();
        printf("结果是a+b = %d
", (a + b));
        push(a + b);
        break;
    case '-':
        a = pop();
        b = pop();
        printf("结果是a-b = %d
", (a - b));
        push(a - b);
        break;
    case '*':
        a = pop();
        b = pop();
        printf("结果是a*b = %d
", (a*b));
        push(a*b);
        break;
    case '/':
        a = pop();
        b = pop();
        printf("结果是a/b = %d
", (a / b));
        push(a / b);
        break;
    default:
        printf("请输入正确操作符
");
    }

    getchar();
    return 0;
}