Calculate how long a program took to run?

[pooshi]

Hello All. I have this simple program here and I want to know how long it took run. Would I use system clock or something out of the time.h?

#include <iostream>
using namespace std;

int main()
{
        int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

	for( int i = 0; i < 9; i++ )
		cout << a[i] << " ";
	                                                                     
	cout << endl;
	system("pause");
	return 0;
}

The output is: 0 1 2 3 4 5 6 7 8
and I want to add: And it took ????? seconds to run.

Thanks for the help,
pooshi

[roberts]

A program that small will almost always run < 1s, unless there is resource contention on a multi-tasking OS.

I wrote a brief program a month or so ago that profiled the time required to compute an object's relativistic mass(1 sqrt, one division, 3 multiplies) 10,000 times. It ran well under a second.

You'll need a high resolution timer and the functionality is OS dependent. For Windows, look up QueryPerformanceFrequency and QueryPerformanceCounter.

For Linux look at clock.

If you're running Windows, add this to your program:

// variables to add
	_int64 countspersec, curr_time, prev_time;
	double secpercount;


// Get the counts per second for the HR timer and calculate the number of seconds one count corresponds to.
	QueryPerformanceFrequency((LARGE_INTEGER*)&countspersec);
	secpercount = 1.0 / (double)countspersec;

// sandwich your code between these two calls
	QueryPerformanceCounter((LARGE_INTEGER*)&prev_time);
	QueryPerformanceCounter((LARGE_INTEGER*)&curr_time);


// reporting code
	cout << "Counts it took to run: " << curr_time - prev_time << endl;
	cout << "Seconds it took to run: " << (curr_time - prev_time) * secpercount << endl;

[pooshi]

Roberts,

I did as instructed and I had to add a windows header file. I got a ton of errors when I ran it. I working on a system with Windows 7 and using VS 2010.

#include <iostream>
#include <WinBase.h>
using namespace std;

int main()
{                                                                                                                                                                      
	
	_int64 countspersec, curr_time, prev_time;
	double secpercount;

	QueryPerformanceCounter( ( LARGE_INTEGER* ) &countspersec );
	secpercount = 1.0 / ( double ) countspersec; 

	QueryPerformanceCounter( ( LARGE_INTEGER* ) &prev_time );
	QueryPerformanceCounter( ( LARGE_INTEGER* ) &curr_time );


	int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

	for( int i = 0; i < 9; i++ )
		cout << a[i] << " ";

	cout << "Counts it took to run: " << curr_time - prev_time << endl;
	cout << "Seconds it took to run: " << (curr_time - prev_time) * secpercount << endl;
	                                                                     
	cout << endl;
	system("pause");
	return 0;
}

1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\winbase.h(243): error C2146: syntax error : missing ';' before identifier 'Internal'
1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\winbase.h(243): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\winbase.h(243): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

These are just a couple of errors I got. Most of the rest say pretty much the same thing.
Any ideas?

Thanks,
Bob

[roberts]

Do you have the win32 SDK installed?

Also, when I said:

// sandwich your code between these two calls
QueryPerformanceCounter((LARGE_INTEGER*)&prev_time);
QueryPerformanceCounter((LARGE_INTEGER*)&curr_time);

You should have:

	QueryPerformanceCounter( ( LARGE_INTEGER* ) &prev_time );



	int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

	for( int i = 0; i < 9; i++ )
		cout << a[i] << " ";
	QueryPerformanceCounter( ( LARGE_INTEGER* ) &curr_time );

[Athar]

And the first function call with countspersec should be QueryPerformanceFrequency.

[roberts]

Also, don't include winbase.h, rather, include windows.h.

The error messages are flagging:

typedef struct _OVERLAPPED {
    ULONG_PTR Internal;
    ULONG_PTR InternalHigh;
    union {
        struct {
            DWORD Offset;
            DWORD OffsetHigh;
        } DUMMYSTRUCTNAME;
        PVOID Pointer;
    } DUMMYUNIONNAME;

    HANDLE  hEvent;
} OVERLAPPED, *LPOVERLAPPED;

Which tells me it's not recognizing ULONG or PTR as valid typedefs. The online doc at MS says the functions are defined in WinBase.h, but that you should include windows.h.

[pooshi]

Thanks guys. The windows.h header file did the trick.
The output is ridiculous:
0 1 2 3 4 5 6 7 8
Counts it took to run: 8512
Seconds it took to run: 0.00344921.

Thanks again. Never knew you could do that,
Bob

[roberts]

That took a surprisingly long time to run. It must be the output functionality that is slowing it down.

#include <Windows.h>
#include <iostream>
#include <cmath>
#include <iostream>

using namespace std;

int main( int argc, char *argv[] )
{
// variables to add
	_int64 countspersec, curr_time, prev_time;
	double secpercount;
	double rel_mass, rest_mass = 5000000000, v = 100000, c = 299792458;

// Get the counts per second for the HR timer and calculate the number of seconds one count corresponds to.
	QueryPerformanceFrequency((LARGE_INTEGER*)&countspersec);
	secpercount = 1.0 / (double)countspersec;

// sandwich your code between these two calls
	QueryPerformanceCounter((LARGE_INTEGER*)&prev_time);
	for( int i = 0; i < 10000; i++ )
		rel_mass = sqrt( rest_mass/(sqrt(1-(v*v)/(c*c))));

	QueryPerformanceCounter((LARGE_INTEGER*)&curr_time);


// reporting code
	cout << "Counts it took to run: " << curr_time - prev_time << endl;
	cout << "Seconds it took to run: " << (curr_time - prev_time) * secpercount << endl;
	cin.get();

}

Counts it took to run: 788
Seconds it took to run: 0.000268996

And I even have the equation wrong (superfluous sqrt in there).