How do I count how many milliseconds it takes my program to run?

Question

This will show how many seconds:

#include <iostream>
#include <time.h>
using namespace std;
int main(void)
{
    int times,timed;

    times=time(NULL);
    //CODE HERE

    timed=time(NULL);
    times=timed-times;
    cout << "time from start to end" << times;
}

This will show how many ticks:

#include <iostream>
#include <time.h>
using namespace std;
int main(void)
{
    int times,timed;

    times=clock();
    //CODE HERE

    timed=clock();
    times=timed-times;
    cout << "ticks from start to end" << times;
}

How do I get milliseconds?

Answer 1

If you use a Unix OS, like Linux or Mac OS X, you can go to the command line and use the line

time call-program

The time command times how long the execution of any command line takes, and reports that to you.

I don't know if there's something like that for Windows, nor how you can measure miliseconds inside a C/C++ program, though.

Answer 2

Refer to question "Convert Difference between 2 times into Milliseconds" on Stack Overflow.

Or use this:

static double diffclock(clock_t clock1,clock_t clock2)
{
    double diffticks=clock1-clock2;
    double diffms=(diffticks)/(CLOCKS_PER_SEC/1000);
    return diffms;
}

Answer 3

There's a CLOCKS_PER_SEC macro to help you convert ticks to milliseconds.

There are O/S-specific APIs to get high-resolution timers.

You can run your program more than once (e.g. a 1000 times) and measure that using a low-resolution timer (e.g. some number of seconds), and then divide that total by the number of times you ran it to get a (higher-resolution) average time.

Answer 4

In Windows, you can use GetTickCount, which is in milliseconds.

Answer 5

Under Win32, you can access the high-resolution timer using QueryPerformanceFrequency and QueryPerformanceCounter (IMHO that should be preferred, possibly with fallback to GetTickCount). You can find the example in Community Content section on MSDN.