C++ 時間字串的格式化輸出
阿新 • • 發佈:2022-03-25
1.Linux系統函式 gettimeofday, 毫秒級時間戳,需要包含標頭檔案 #include <sys/time.h>
static std::string getCurrentTime() { struct timeval tv; gettimeofday(&tv, NULL); static constexpr size_t MAX_BUFFER_SIZE = 128; char buff[MAX_BUFFER_SIZE + 1]; time_t sec = static_cast<time_t>(tv.tv_sec); int ms = static_cast<int>(tv.tv_usec) / 1000; struct tm tm_time; localtime_r(&sec, &tm_time); static const char *formater = "%4d-%02d-%02d %02d:%02d:%02d.%03d"; int ret = snprintf(buff, MAX_BUFFER_SIZE, formater, tm_time.tm_year + 1900, tm_time.tm_mon + 1, tm_time.tm_mday, tm_time.tm_hour, tm_time.tm_min, tm_time.tm_sec, ms); if (ret < 0) { return std::string(""); } return std::string(buff); }
2.使用C++標準庫函式 std::chrono
static std::string FormatTimePoint(const std::chrono::system_clock::time_point &time_point, const std::string &format = "%Y-%m-%d %X") { auto in_time_t = std::chrono::system_clock::to_time_t(time_point); std::stringstream ss; ss << std::put_time(std::localtime(&in_time_t), format.c_str()); return ss.str(); }
使用方法如下:
int main()
{
// 方法一
std::cout << getCurrentTime() << std::endl;
// 方法二
const std::chrono::time_point<std::chrono::system_clock> now =
std::chrono::system_clock::now();
std::cout << FormatTimePoint(now) << std::endl;
return 0;
}
結果輸出:
2022-03-25 12:17:57.336 2022-03-25 12:17:57 Process finished with exit code 0