How to use QueryPerformanceCounter to test performance of existing code? - c++

Question

I have an existing project in Visual Studio, with a main file that calls a function file. I also created a CodeTimer.cpp following the steps from the Microsoft guide, and I placed it along with the necessary headers in the same directory as my code and function.
The issue is, I don't know how to link them. The solution builds fine, all three files combine with no errors. But when I CTRL-F5 it, I just see the output of my main, for obvious reasons (I didn't link the CodeTimer to the main).
This is my CodeTimer:
#include "stdafx.h"
#include <tchar.h>
#include <windows.h>
using namespace System;
int _tmain(int argc, _TCHAR* argv[])
{
__int64 ctr1 = 0, ctr2 = 0, freq = 0;
int acc = 0, i = 0;
// Start timing the code.
if (QueryPerformanceCounter((LARGE_INTEGER *)&ctr1) != 0)
{
// Code segment is being timed.
for (i = 0; i<100; i++) acc++;
// Finish timing the code.
QueryPerformanceCounter((LARGE_INTEGER *)&ctr2);
Console::WriteLine("Start Value: {0}", ctr1.ToString());
Console::WriteLine("End Value: {0}", ctr2.ToString());
QueryPerformanceFrequency((LARGE_INTEGER *)&freq);
Console::WriteLine("QueryPerformanceFrequency : {0} per Seconds.", freq.ToString());
Console::WriteLine("QueryPerformanceCounter minimum resolution: 1/{0} Seconds.", freq.ToString());
Console::WriteLine("ctr2 - ctr1: {0} counts.", ((ctr2 - ctr1) * 1.0 / 1.0).ToString());
Console::WriteLine("65536 Increments by 1 computation time: {0} seconds.", ((ctr2 - ctr1) * 1.0 / freq).ToString());
}
else
{
DWORD dwError = GetLastError();
Console::WriteLine("Error value = {0}", dwError.ToString());
}
// Make the console window wait.
Console::WriteLine();
Console::Write("Press ENTER to finish.");
Console::Read();
return 0;
}

Answer 1

NVM fixed it. Just had to add the body of _tmain() in main() function under my code, and get ride of the CodeTimer.cpp file completely. It was a conflict of mains (multiple mains in one project, the compiler automatically outputted the one with the highest priority in the project).