Get current time and date in C++

This post will discuss how to get the current time and date in C++.

1. Using `std::chrono`

Since C++11, the standard solution to get the current time and date in C++ is using chrono library. We can get the current time with std::chrono::system_clock::now() from the <chrono.h> header, and convert it to a std::time_t type (time since epoch). Then, convert the std::time_t to a local calendar time std::ctime in Www Mmm dd hh:mm:ss yyyy format, as shown below:

#include <iostream>

#include <chrono>

int main()

{

auto now = std::chrono::system_clock::now();

std::time_t end_time = std::chrono::system_clock::to_time_t(now);

std::cout << "Current Time and Date: " << std::ctime(&end_time) << std::endl;

return 0;

}

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Output (will vary):

Current Time and Date: Tue Feb 08 18:40:13 2018

If you just need to measure elapsed time in C++, do as follows.

#include <iostream>

#include <chrono>

int main()

{

auto start = std::chrono::system_clock::now();

// do some work

for (int i = 0; i < 10000000; i++) {}

auto end = std::chrono::system_clock::now();

std::chrono::duration<double> elapsed_seconds = end - start;

std::cout << "Elapsed Time: " << elapsed_seconds.count() << " sec" << std::endl;

return 0;

}

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Output (will vary):

Elapsed Time: 0.060156 sec

Since C++20, we can also use std::chrono::zoned_time for representing date and time with a time-zone.

#include <iostream>

#include <chrono>

int main()

{

std::chrono::zoned_time now { std::chrono::current_zone(),

std::chrono::system_clock::now() };

std::cout << "Current Time and Date: " << std::endl;

return 0;

}

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2. Using `std::time`

The idea is to get the number of seconds elapsed since epoch as std::time_t value, and then convert it into an std::tm instance with std::localtime. An std::tm object holds a calendar date and time broken down into its components (sec, min, hour, day, month, year, etc.).

The following code example demonstrates its usage. Note that this solution needs <ctime> header.

#include <iostream>

#include <ctime>

int main()

{

std::time_t t = std::time(nullptr);

std::tm* now = std::localtime(&t);

std::cout << "Current Date: " << now->tm_mday << '/' << (now->tm_mon + 1) << '/'

<< (now->tm_year + 1900) << std::endl;

return 0;

}

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Output (will vary):

Current Date: 8/2/2018

We can further convert date and time information from the std::tm object to a null-terminated multibyte character, according to the specified format string using the strftime() function. For example, the following code returns the current date and time as std::string in the format MM-DD-YYYY HH:mm:ss.

#include <iostream>

#include <string>

#include <ctime>

std::string currentDateTime() {

std::time_t t = std::time(nullptr);

std::tm* now = std::localtime(&t);

char buffer[128];

strftime(buffer, sizeof(buffer), "%m-%d-%Y %X", now);

return buffer;

}

int main()

{

std::cout << "Current Time and Date: " << currentDateTime() << std::endl;

return 0;

}

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Output (will vary):

Current Time and Date: 02-08-2018 18:42:41

3. Using `Boost.Date_Time`

Another option is to use the date-time functions offered by the boost library. There are several time systems available by boost library. The following solution uses boost::posix_time::microsec_clock::universal_time from the header <boost/date_time/posix_time/posix_time> – that return the time in UTC.

#include <iostream>

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

int main()

{

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

std::cout << "Current Time and Date: " << datetime << std::endl;

return 0;

}

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Output (will vary):

Current Time and Date: 2018-Feb-08 18:42:41.804879

That’s all about getting the current time and date in C++.

Get current time and date in C++

1. Using std::chrono

2. Using std::time

3. Using Boost.Date_Time

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1. Using `std::chrono`

2. Using `std::time`

3. Using `Boost.Date_Time`