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POWhy is .NET faster than C++ in this case?
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copied!<p><strong>Make sure you run outside of the IDE.</strong> That is key.</p> <p>-edit- I LOVE SLaks comment. "The amount of misinformation in these answers is staggering." :D</p> <p>Calm down guys. Pretty much all of you were wrong. I DID make optimizations. <strike>It turns out whatever optimizations I made wasn't good enough.</strike> I ran the code in GCC using gettimeofday (I'll paste code below) and used <code>g++ -O2 file.cpp</code> and got slightly faster results then C#. <strike>Maybe MS didn't create the optimizations needed in this specific case but after downloading and installing mingw I was tested and found the speed to be near identical.</strike> <a href="https://stackoverflow.com/questions/2285864/why-is-net-faster-than-c-in-this-case/2286084#2286084">Justicle</a> Seems to be right. I could have sworn I use clock on my PC and used that to count and found it was slower but problem solved. C++ speed isn't almost twice as slower in the MS compiler.</p> <p>When my friend informed me of this I couldn't believe it. So I took his code and put some timers onto it.</p> <p>Instead of <a href="http://en.wikipedia.org/wiki/Boo_%28programming_language%29" rel="nofollow noreferrer">Boo</a> I used C#. I constantly got faster results in C#. Why? The .NET version was nearly half the time no matter what number I used.</p> <p>C++ version (bad version):</p> <pre><code>#include <iostream> #include <stdio.h> #include <intrin.h> #include <windows.h> using namespace std; int fib(int n) { if (n < 2) return n; return fib(n - 1) + fib(n - 2); } int main() { __int64 time = 0xFFFFFFFF; while (1) { int n; //cin >> n; n = 41; if (n < 0) break; __int64 start = __rdtsc(); int res = fib(n); __int64 end = __rdtsc(); cout << res << endl; cout << (float)(end-start)/1000000<<endl; break; } return 0; } </code></pre> <p>C++ version (better version):</p> <pre><code>#include <iostream> #include <stdio.h> #include <intrin.h> #include <windows.h> using namespace std; int fib(int n) { if (n < 2) return n; return fib(n - 1) + fib(n - 2); } int main() { __int64 time = 0xFFFFFFFF; while (1) { int n; //cin >> n; n = 41; if (n < 0) break; LARGE_INTEGER start, end, delta, freq; ::QueryPerformanceFrequency( &freq ); ::QueryPerformanceCounter( &start ); int res = fib(n); ::QueryPerformanceCounter( &end ); delta.QuadPart = end.QuadPart - start.QuadPart; cout << res << endl; cout << ( delta.QuadPart * 1000 ) / freq.QuadPart <<endl; break; } return 0; } </code></pre> <p>C# version:</p> <pre><code>using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; using System.ComponentModel; using System.Threading; using System.IO; using System.Diagnostics; namespace fibCSTest { class Program { static int fib(int n) { if (n < 2)return n; return fib(n - 1) + fib(n - 2); } static void Main(string[] args) { //var sw = new Stopwatch(); //var timer = new PAB.HiPerfTimer(); var timer = new Stopwatch(); while (true) { int n; //cin >> n; n = 41; if (n < 0) break; timer.Start(); int res = fib(n); timer.Stop(); Console.WriteLine(res); Console.WriteLine(timer.ElapsedMilliseconds); break; } } } } </code></pre> <p>GCC version:</p> <pre><code>#include <iostream> #include <stdio.h> #include <sys/time.h> using namespace std; int fib(int n) { if (n < 2) return n; return fib(n - 1) + fib(n - 2); } int main() { timeval start, end; while (1) { int n; //cin >> n; n = 41; if (n < 0) break; gettimeofday(&start, 0); int res = fib(n); gettimeofday(&end, 0); int sec = end.tv_sec - start.tv_sec; int usec = end.tv_usec - start.tv_usec; cout << res << endl; cout << sec << " " << usec <<endl; break; } return 0; } </code></pre>

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