1 time_t
time_t 计时精确秒，就是相当于获取当时的时间
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| #include <time.h>
time_t t;
struct tm *timeinfo;
time(&t);
timeinfo = localtime(&t);
printf("%s", asctime(timeinfo));
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2 clock_t
clock_t 获取的是进程调用 CPU 的时间，多核情况下不准确
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| #include <time.h>
clock_t start, finish;
start = clock();
finish = clock();
printf("main: %f ms\n", ((double)(finish - start) / 1000));
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3 gettimeofday
这种方式可以精确到微秒获取程序运行耗费的时间
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| #include <sys/time.h>
struct timeval start, end;
gettimeofday(&start, NULL);
gettimeofday(&end1, NULL);
double timeuse = (double)(1000000 * (end1.tv_sec - start1.tv_sec) + (end1.tv_usec - start1.tv_usec)) / 1000;
printf("%f\n", timeuse);
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4 std::chrono
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| #include <chrono>
struct Timer
{
std::chrono::system_clock::time_point start, end;
std::chrono::duration<float> duration;
Timer()
{
start = std::chrono::high_resolution_clock::now();
}
~Timer()
{
end = std::chrono::high_resolution_clock::now();
duration = end - start;
const float seconds = duration.count();
if (seconds < 1) {
std::cout << "Timer took " << seconds * 1000.0f << "ms" << std::endl;
} else if (seconds < 60) {
std::cout << "Timer took " << seconds << "s" << std::endl;
} else {
std::cout << "Timer took " << seconds / 60 << "min" << std::endl;
}
}
};
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