Measuring execution time of a function in C++

Question

I want to find out how much time a certain function takes in my C++ program to execute on Linux. Afterwards, I want to make a speed comparison . I saw sever

Answer 1

• It is a very easy to use method in C++11.
• We can use std::chrono::high_resolution_clock from header
• We can write a method to print the method execution time in a much readable form.

For example, to find the all the prime numbers between 1 and 100 million, it takes approximately 1 minute and 40 seconds. So the execution time get printed as:

Execution Time: 1 Minutes, 40 Seconds, 715 MicroSeconds, 715000 NanoSeconds

The code is here:

#include 
#include 

using namespace std;
using namespace std::chrono;

typedef high_resolution_clock Clock;
typedef Clock::time_point ClockTime;

void findPrime(long n, string file);
void printExecutionTime(ClockTime start_time, ClockTime end_time);

int main()
{
    long n = long(1E+8);  // N = 100 million

    ClockTime start_time = Clock::now();

    // Write all the prime numbers from 1 to N to the file "prime.txt"
    findPrime(n, "C:\\prime.txt"); 

    ClockTime end_time = Clock::now();

    printExecutionTime(start_time, end_time);
}

void printExecutionTime(ClockTime start_time, ClockTime end_time)
{
    auto execution_time_ns = duration_cast(end_time - start_time).count();
    auto execution_time_ms = duration_cast(end_time - start_time).count();
    auto execution_time_sec = duration_cast(end_time - start_time).count();
    auto execution_time_min = duration_cast(end_time - start_time).count();
    auto execution_time_hour = duration_cast(end_time - start_time).count();

    cout << "\nExecution Time: ";
    if(execution_time_hour > 0)
    cout << "" << execution_time_hour << " Hours, ";
    if(execution_time_min > 0)
    cout << "" << execution_time_min % 60 << " Minutes, ";
    if(execution_time_sec > 0)
    cout << "" << execution_time_sec % 60 << " Seconds, ";
    if(execution_time_ms > 0)
    cout << "" << execution_time_ms % long(1E+3) << " MicroSeconds, ";
    if(execution_time_ns > 0)
    cout << "" << execution_time_ns % long(1E+6) << " NanoSeconds, ";
}