c++时间戳获取和转换

<>1、使用api

可以使用windows下和linux下api函数来获取，比较简单，如下所示：
int64_t getTimeStamp() { //毫秒数 int mSecond = 0; #if defined(WIN32) SYSTEMTIME
sys; GetLocalTime(&sys); mSecond = sys.wMilliseconds; #else //linux
下gettimeofday struct timeval tv; struct timezone tz; struct tm* p; gettimeofday(
&tv, &tz); p = localtime(&tv.tv_sec); mSecond = tv.tv_usec / 1000; #endif
int64_t timeStamp = ((int64_t)time(NULL)) * 1000 + mSecond; return timeStamp; }
<>2、使用标准c++函数

使用标准c++就没有那么多麻烦了
std::chrono::time_point<std::chrono::system_clock, std::chrono::milliseconds>
tpMicro= std::chrono::time_point_cast<std::chrono::milliseconds>(std::chrono::
system_clock::now()); time_t timeStamp2 = tpMicro.time_since_epoch().count();
<>3、时间转time_t

对于一些不标准的字符串时间，我们需要转换时，可以十一用sscanf函数，windows下使用sscanf_s
time_t StringToDatetime(const char* str) { tm tm_; int year, month, day, hour,
minute, second; sscanf_s(str, "%d/%d/%d %d:%d:%d", &day, &month, &year, &hour, &
minute, &second); tm_.tm_year = year - 1900; tm_.tm_mon = month - 1; tm_.tm_mday
= day; tm_.tm_hour = hour; tm_.tm_min = minute; tm_.tm_sec = second; tm_.
tm_isdst= 0; time_t t_ = mktime(&tm_); //已经减了8个时区 return t_; //秒时间 }
<>4 、调用
int main() { int64_t timeStamp = getTimeStamp(); std::chrono::time_point<std::
chrono::system_clock, std::chrono::milliseconds> tpMicro = std::chrono::
time_point_cast<std::chrono::milliseconds>(std::chrono::system_clock::now());
time_t timeStamp2 = tpMicro.time_since_epoch().count(); std::cout << timeStamp
<< std::endl; std::cout << timeStamp2 << std::endl; std::string a = "1/4/2022
00:00:20"; std::string b = "1/4/2022 00:00:01"; time_t t1 = StringToDatetime(a.
c_str()); time_t t2 = StringToDatetime(b.c_str()); std::cout << t2-t1<<"\n"; }
结果如下所示

可以看出c调用api函数和调用标准c++的结果是一样的。

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