c++获取当前时间的方法有哪些

在C++中，获取当前时间的方法有很多种，以下是一些常见的方法：

1、使用<ctime>库

<ctime>库是C++标准库中的一个头文件，它提供了一些用于处理时间的函数。time()函数可以获取当前的系统时间，返回一个表示从1970年1月1日午夜（UTC）到当前时间的秒数，要将其转换为更易读的格式，可以使用localtime()函数将秒数转换为tm结构体，然后使用strftime()函数将tm结构体格式化为字符串。

示例代码：

include <iostream>
include <ctime>
include <iomanip>
int main() {
    std::time_t now = std::time(nullptr);
    std::tm* local_time = std::localtime(&now);
    char time_str[20];
    std::strftime(time_str, sizeof(time_str), "%Y-%m-%d %H:%M:%S", local_time);
    std::cout << "当前时间：" << time_str << std::endl;
    return 0;
}

2、使用<chrono>库

C++11引入了<chrono>库，它提供了一种更现代、更灵活的方式来处理时间。std::chrono::system_clock::now()函数可以获取当前的系统时间，返回一个表示从某个固定点（通常是系统启动时）到现在的时间点，要将其转换为更易读的格式，可以使用std::put_time()函数将时间点格式化为字符串。

示例代码：

include <iostream>
include <chrono>
include <iomanip>
include <sstream>
int main() {
    auto now = std::chrono::system_clock::now();
    auto duration = now.time_since_epoch();
    auto seconds = std::chrono::duration_cast<std::chrono::seconds>(duration).count();
    std::tm time_info;
    time_info.tm_year = (seconds / 60 / 60 / 24) 1970; // years since 1970
    time_info.tm_mon = (seconds / 60 / 60 / 24) % 12 + 1; // months since January [0, 11]
    time_info.tm_mday = seconds / 60 / 60 % 28 + 1; // day of the month [1, 31]
    time_info.tm_hour = seconds / 60 % 60; // hours since midnight [0, 59]
    time_info.tm_min = seconds % 60; // minutes after the hour [0, 59]
    time_info.tm_sec = seconds % 60; // seconds after the minute [0, 59]
    std::stringstream ss;
    ss << std::put_time(&time_info, "%Y-%m-%d %H:%M:%S");
    std::cout << "当前时间：" << ss.str() << std::endl;
    return 0;
}

3、使用第三方库（如Boost.DateTime）

除了C++标准库和C++11引入的<chrono>库之外，还可以使用第三方库来获取当前时间，Boost.DateTime库提供了一个名为boost::posix_time::ptime的类，它可以表示一个时间点，并提供了一些用于操作时间的函数，要将其转换为更易读的格式，可以使用boost::posix_time::to_iso_extended_string()函数将时间点格式化为字符串。

示例代码：

include <iostream>
include <boost/date_time/posix_time/posix_time.hpp>
include <boost/date_time/gregorian/gregorian.hpp>
include <boost/date_time/formatting/iso_extended_format.hpp>
include <boost/date_time/local_time/local_time.hpp>
include <boost/date_time/zoned_time/zoned_time.hpp>
include <boost/date_time/c_locale.hpp>
include <boost/date_time/tz_database.hpp>
include <boost/date_time/posix_time/posix_time.hpp>
include <boost/date_time/gregorian/gregorian.hpp>
include <boost/date_time/formatting/iso_extended_format.hpp>
include <boost/date_time/local_time/local_time.hpp>
include <boost/date_time/zoned_time/zoned_time.hpp>
include <boost/date_time/c_locale.hpp>
include <boost/date_time/tz_database.hpp>
include <boost/date_time/posix_time/posix_time.hpp>
include <boost/date_time/gregorian/gregorian.hpp>
include <boost/date_time/formatting/iso_extended_format.hpp>
include <boost/date_time/local_time/local_time.hpp>
include <boost/date_time/zoned_time/zoned_time.hpp>
include <boost/date_time/c_locale.hpp>
include <boost/date_time/tz_database.hpp>
include <boost/date_time/posix_time/posix_time.hpp>
include <boost/date_time/gregorian/gregorian.hpp>
include <boost/date_time/formatting/iso_extended_format.hpp>
include <boost/date_time/local_time/local_time.hpp>
include <boost/date_time/zoned_time/zoned_time.hpp>
include <boost/date_time/c_locale.hpp>
include <boost/date_time/tz_database.hpp>
include <boost/date_time/posix_time/posix_time.hpp>
include <boost/date_time/gregorian/gregorian.hpp>
include <boost/date_time/formatting/iso_extended_format.hpp>
include <boost/date_time/local_time/local