Measure elapsed time of a C++ program using chrono library

In this post, we will discuss how to measure elapsed time of a C++ program in seconds, milliseconds, microseconds and nanoseconds using chrono library.

Since C++11, the best way to measure elapsed time in C++ is by using the chrono library which deal with time.

Below C++ program calculates the time elapsed for a simple code, in seconds, milliseconds, microseconds and nanoseconds. It includes the <chrono.h> header which provides access to the current time using system_clock(). The system_clock is designed to represent the real time and used by all processes running on the system.

#include <iostream>
#include <chrono>
#include <unistd.h>

using namespace std;

// main function to measure elapsed time of a C++ program 
// using chrono library
int main()
{
	auto start = chrono::steady_clock::now();

	// do some stuff here
	sleep(3);

	auto end = chrono::steady_clock::now();

	cout << "Elapsed time in nanoseconds : " 
		<< chrono::duration_cast<chrono::nanoseconds>(end - start).count()
		<< " ns" << endl;

	cout << "Elapsed time in microseconds : " 
		<< chrono::duration_cast<chrono::microseconds>(end - start).count()
		<< " µs" << endl;

	cout << "Elapsed time in milliseconds : " 
		<< chrono::duration_cast<chrono::milliseconds>(end - start).count()
		<< " ms" << endl;

	cout << "Elapsed time in seconds : " 
		<< chrono::duration_cast<chrono::seconds>(end - start).count()
		<< " sec";

	return 0;
}

#include <iostream>

#include <chrono>

#include <unistd.h>

using namespace std;

// main function to measure elapsed time of a C++ program

// using chrono library

int main()

{

auto start = chrono::steady_clock::now();

// do some stuff here

sleep(3);

auto end = chrono::steady_clock::now();

cout << "Elapsed time in nanoseconds : "

<< chrono::duration_cast<chrono::nanoseconds>(end - start).count()

<< " ns" << endl;

cout << "Elapsed time in microseconds : "

<< chrono::duration_cast<chrono::microseconds>(end - start).count()

<< " µs" << endl;

cout << "Elapsed time in milliseconds : "

<< chrono::duration_cast<chrono::milliseconds>(end - start).count()

<< " ms" << endl;

cout << "Elapsed time in seconds : "

<< chrono::duration_cast<chrono::seconds>(end - start).count()

<< " sec";

return 0;

}

Download Run Code

Output (may vary):

Elapsed time in nanoseconds : 3000090354 ns
Elapsed time in microseconds : 3000090 µs
Elapsed time in milliseconds : 3000 ms
Elapsed time in seconds : 3 sec

Related Post: Find the execution time of a C program

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