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时间转本地时间

下面的例子，获取文件最后修改时间，并转换为本地时间：

    std::filesystem::path p{u8"D:/1.csv"};std::chrono::file_time pFile = std::filesystem::last_write_time(p);std::chrono::zoned_time  zt { std::chrono::current_zone() ,std::chrono::clock_cast<std::chrono::system_clock>(pFile) };

时间转字符串：

    std::chrono::zoned_time  zt { std::chrono::current_zone() ,std::chrono::clock_cast<std::chrono::system_clock>(pFile) };{std::string str = std::format("{0:%Y}-{0:%m}-{0:%d} {0:%OH}:{0:%M}:{0:%S}", zt.get_sys_time());std::cout << str << std::endl;}

字符串转时间

 std::chrono::sys_time<std::chrono::milliseconds> t;{std::stringstream s;s << str;std::chrono::from_stream(s, "%F %T", t);std::cout << t << std::endl;}

完整代码如下:

#include <filesystem>
#include <iostream>
#include <format>int main()
{   std::filesystem::path p{u8"D:/1.csv"};//从文件获取最后写入时间std::chrono::file_time pFile = std::filesystem::last_write_time(p);//转本地时间std::chrono::zoned_time  zt { std::chrono::current_zone() ,std::chrono::clock_cast<std::chrono::system_clock>(pFile) };{//时间（utc)转字符串std::string str = std::format("{0:%Y}-{0:%m}-{0:%d} {0:%OH}:{0:%M}:{0:%S}", zt.get_sys_time());std::cout << str << std::endl;}{//时间（本地）转字符串std::string str = std::format("{0:%F} {0:%T}", zt.get_local_time());std::cout << str << std::endl;{//字符串转时间std::chrono::sys_time<std::chrono::milliseconds> t;std::stringstream s;s << str;std::chrono::from_stream(s, "%F %T", t);std::cout << t << std::endl;}}   getchar();return 0;
}

运行结果如下：

2024-07-01 05:24:02.0000000
2024-07-01 13:24:02.0000000
2024-07-01 13:24:02.000

时间转年月日时分秒

c++20时间转年月日代码如下：

转年月日：

std::chrono::year_month_day ymd{ std::chrono::floor< std::chrono::days>(zt.get_local_time()) };

转时分秒：

std::chrono::hh_mm_ss hms { zt.get_local_time() - std::chrono::floor<std::chrono::days>(zt.get_local_time()) };    

完整代码如下：

#include <iostream>
#include <chrono>int main()
{//获取当前时间std::chrono::time_point fNow = std::chrono::system_clock::now();std::chrono::zoned_time  zt{ std::chrono::current_zone() ,std::chrono::clock_cast<std::chrono::system_clock>(fNow) };   //输出年月日std::chrono::year_month_day ymd{ std::chrono::floor< std::chrono::days>(zt.get_local_time()) };std::cout << ymd.year().operator int() << "-" << ymd.month().operator unsigned int() << "-" << ymd.day().operator unsigned int() << std::endl;//输出时分秒std::chrono::hh_mm_ss hms { zt.get_local_time() - std::chrono::floor<std::chrono::days>(zt.get_local_time()) };    std::cout << hms.hours().count() << ":" << hms.minutes().count() << ":" << hms.seconds().count() << std::endl;getchar();
}

输出结果：

2024-10-31
9:30:52