起因
在写代码的时候经常需要比对两个版本之间代码的速度， 每当这个时候都要重新写一遍获取时间的代码，然后格式化输出。虽然可以参考之前的代码来复制粘贴，但是这样我还是嫌麻烦，所以就有了这一段代码。
实现方式
我想使用最简单的方式来计时，最好是直接输入一行代码就可以，而且不能依赖额外的库,所以我使用了宏定义的形式。尝试了一下使用一行代码会比较繁琐，所以需要添加两行代码来统计。
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#ifndef _SHOWTIME_
#define _SHOWTIME_
#include <stdio.h>
#include <time.h>
#include <stdint.h>
#define BILLION 1000000000L
#define TIME_START(__in_run_times, run_name) do { \
int __run_times = __in_run_times; \
char *__run_name = run_name; \
uint64_t diff = 0; \
struct timespec _show_time_start_, _show_time_end_; \
for (int __i = 0; __i < __run_times; __i++) { \
clock_gettime(CLOCK_MONOTONIC, &_show_time_start_)
#define TIME_END \
clock_gettime(CLOCK_MONOTONIC, &_show_time_end_); \
diff += (BILLION * (_show_time_end_.tv_sec - _show_time_start_.tv_sec) + \
_show_time_end_.tv_nsec - _show_time_start_.tv_nsec); \
} \
printf("\n[%s Time] Run %d times\n", __run_name, __run_times); \
printf("[%s Time] Total:\t%llu ns or %llu us\n", \
__run_name, \
(long long unsigned int) diff, \
(long long unsigned int) diff / (1000)); \
printf("[%s Time] Mean: \t%llu ns or %llu us\n", \
__run_name, \
(long long unsigned int) diff / __run_times, \
(long long unsigned int) diff / (1000 * __run_times)); \
} while(0)
#endif
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如何使用
使用起来就更加简单了, 代码如下，编译即可。
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| #include "showtime.h"
int main(void)
{
TIME_START(30, "Test");
printf("Test show time!\n");
TIME_END;
return 0;
}
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输出如下：
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| ./test_t
Test show time!
Test show time!
Test show time!
... ...
Test show time!
[Test Time] Run 30 times
[Test Time] Total: 225318 ns or 225 us
[Test Time] Mean: 7510 ns or 7 us
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