(给谷歌人)

还有Boost::date_time:

#include <boost/date_time/posix_time/posix_time.hpp>

boost::posix_time::ptime date_time = boost::posix_time::microsec_clock::universal_time();

这为我在Linux (RHEL)和Windows (x64)上编译，目标是g++和OpenMP:

#include <ctime>
#include <iostream>
#include <string>
#include <locale>

////////////////////////////////////////////////////////////////////////////////
//
//  Reports a time-stamped update to the console; format is:
//       Name: Update: Year-Month-Day_of_Month Hour:Minute:Second
//
////////////////////////////////////////////////////////////////////////////////
//
//  [string] strName  :  name of the update object
//  [string] strUpdate:  update descripton
//          
////////////////////////////////////////////////////////////////////////////////

void ReportTimeStamp(string strName, string strUpdate)
{
    try
    {
        #ifdef _WIN64
            //  Current time
            const time_t tStart = time(0);
            //  Current time structure
            struct tm tmStart;

            localtime_s(&tmStart, &tStart);

            //  Report
            cout << strName << ": " << strUpdate << ": " << (1900 + tmStart.tm_year) << "-" << tmStart.tm_mon << "-" << tmStart.tm_mday << " " << tmStart.tm_hour << ":" << tmStart.tm_min << ":" << tmStart.tm_sec << "\n\n";
        #else
            //  Current time
            const time_t tStart = time(0);
            //  Current time structure
            struct tm* tmStart;

            tmStart = localtime(&tStart);

            //  Report
            cout << strName << ": " << strUpdate << ": " << (1900 + tmStart->tm_year) << "-" << tmStart->tm_mon << "-" << tmStart->tm_mday << " " << tmStart->tm_hour << ":" << tmStart->tm_min << ":" << tmStart->tm_sec << "\n\n";
        #endif

    }
    catch (exception ex)
    {
        cout << "ERROR [ReportTimeStamp] Exception Code:  " << ex.what() << "\n";
    }

    return;
}

#include <iostream>
#include <chrono>
#include <string>
#pragma warning(disable: 4996)
// Ver: C++ 17 
// IDE: Visual Studio
int main() {
    using namespace std; 
    using namespace chrono;
    time_point tp = system_clock::now();
    time_t tt = system_clock::to_time_t(tp);
    cout << "Current time: " << ctime(&tt) << endl;
    return 0;
}

auto time = std::time(nullptr);
std::cout << std::put_time(std::localtime(&time), "%F %T%z"); // ISO 8601 format.

使用std::time()或std::chrono::system_clock::now()(或其他时钟类型)获取当前时间。

std::put_time() (c++ 11)和strftime() (C)提供了很多格式化程序来输出这些时间。

#include <iomanip>
#include <iostream>

int main() {
    auto time = std::time(nullptr);
    std::cout
        // ISO 8601: %Y-%m-%d %H:%M:%S, e.g. 2017-07-31 00:42:00+0200.
        << std::put_time(std::gmtime(&time), "%F %T%z") << '\n'
        // %m/%d/%y, e.g. 07/31/17
        << std::put_time(std::gmtime(&time), "%D"); 
}

格式化程序的顺序很重要:

std::cout << std::put_time(std::gmtime(&time), "%c %A %Z") << std::endl;
// Mon Jul 31 00:00:42 2017 Monday GMT
std::cout << std::put_time(std::gmtime(&time), "%Z %c %A") << std::endl;
// GMT Mon Jul 31 00:00:42 2017 Monday

strftime()的格式化器类似:

char output[100];
if (std::strftime(output, sizeof(output), "%F", std::gmtime(&time))) {
    std::cout << output << '\n'; // %Y-%m-%d, e.g. 2017-07-31
}

通常，大写格式器表示“完整版本”，小写格式器表示缩写(例如Y: 2017, Y: 17)。

区域设置改变输出:

#include <iomanip>
#include <iostream>
int main() {
    auto time = std::time(nullptr);
    std::cout << "undef: " << std::put_time(std::gmtime(&time), "%c") << '\n';
    std::cout.imbue(std::locale("en_US.utf8"));
    std::cout << "en_US: " << std::put_time(std::gmtime(&time), "%c") << '\n';
    std::cout.imbue(std::locale("en_GB.utf8"));
    std::cout << "en_GB: " << std::put_time(std::gmtime(&time), "%c") << '\n';
    std::cout.imbue(std::locale("de_DE.utf8"));
    std::cout << "de_DE: " << std::put_time(std::gmtime(&time), "%c") << '\n';
    std::cout.imbue(std::locale("ja_JP.utf8"));
    std::cout << "ja_JP: " << std::put_time(std::gmtime(&time), "%c") << '\n';
    std::cout.imbue(std::locale("ru_RU.utf8"));
    std::cout << "ru_RU: " << std::put_time(std::gmtime(&time), "%c");        
}

可能的输出(Coliru，编译器浏览器):

undef: Tue Aug  1 08:29:30 2017
en_US: Tue 01 Aug 2017 08:29:30 AM GMT
en_GB: Tue 01 Aug 2017 08:29:30 GMT
de_DE: Di 01 Aug 2017 08:29:30 GMT
ja_JP: 2017年08月01日 08時29分30秒
ru_RU: Вт 01 авг 2017 08:29:30

我已经使用std::gmtime()转换为UTC。提供Std::localtime()来转换为本地时间。

注意，在其他答案中提到的asctime()/ctime()现在被标记为已弃用，strftime()应该是首选。

你可以使用boost和chrono库:

#include <iostream>
#include <chrono>
#include <boost/date_time/posix_time/posix_time.hpp>

using boost::posix_time::to_iso_extended_string;
using boost::posix_time::from_time_t;
using std::chrono::system_clock;

int main()
{
  auto now = system_clock::now();
  std::cout << to_iso_extended_string(from_time_t(system_clock::to_time_t(now)));
}

你可以尝试下面的跨平台代码来获取当前的日期/时间:

#include <iostream>
#include <string>
#include <stdio.h>
#include <time.h>

// Get current date/time, format is YYYY-MM-DD.HH:mm:ss
const std::string currentDateTime() {
    time_t     now = time(0);
    struct tm  tstruct;
    char       buf[80];
    tstruct = *localtime(&now);
    // Visit http://en.cppreference.com/w/cpp/chrono/c/strftime
    // for more information about date/time format
    strftime(buf, sizeof(buf), "%Y-%m-%d.%X", &tstruct);

    return buf;
}

int main() {
    std::cout << "currentDateTime()=" << currentDateTime() << std::endl;
    getchar();  // wait for keyboard input
}

输出:

currentDateTime()=2012-05-06.21:47:59

有关日期/时间格式的更多信息，请访问这里