c - 结构部分作为参数 : unknown type name

Question

我正在尝试将结构部分作为参数传递。但是，我在编译时收到以下消息:“未知类型名称‘time1’”。这是导致这些问题的代码部分:

#include <stdio.h>

struct time {
    int hour;
    int minutes;
    int seconds;
};

struct time time1;
struct time time2;
struct time elapsed;

int hourDif (time1.hour, time2.hour) {
    if (time2.hour >= time1.hour) {
        elapsed.hour = time2.hour - time1.hour;
    }
    else {
        elapsed.hour = 24 - (time1.hour - time2.hour);
    }
    return 0;
}

Answer 1

这个

int hourDif (time1.hour, time2.hour)

不是一个函数调用，它是一个函数声明，在你的情况下它也是它的定义，你需要的是

int hourDif (struct time time1, struct time time2)
 {
    int difference;
    difference = 0; /* some compilers might complain */
    if (time2.hour >= time1.hour)
        difference = time2.hour - time1.hour;
    else
        difference = 24 - (time1.hour - time2.hour);
    return difference;
}

然后在代码的某处，不需要全局变量就可以了

struct time time1;
struct time time2;

/* initialize `time1' and `time2' */
int difference  = hourDiff(time1, time2);