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POC# vs C - Big performance difference
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copied!<p>I'm finding massive performance differences between similar code in C anc C#.</p> <p>The C code is:</p> <pre><code>#include <stdio.h> #include <time.h> #include <math.h> main() { int i; double root; clock_t start = clock(); for (i = 0 ; i <= 100000000; i++){ root = sqrt(i); } printf("Time elapsed: %f\n", ((double)clock() - start) / CLOCKS_PER_SEC); } </code></pre> <p>And the C# (console app) is:</p> <pre><code>using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { DateTime startTime = DateTime.Now; double root; for (int i = 0; i <= 100000000; i++) { root = Math.Sqrt(i); } TimeSpan runTime = DateTime.Now - startTime; Console.WriteLine("Time elapsed: " + Convert.ToString(runTime.TotalMilliseconds/1000)); } } } </code></pre> <p>With the above code, the C# completes in 0.328125 seconds (release version) and the C takes 11.14 seconds to run.</p> <p>The c is being compiled to a windows executable using mingw.</p> <p>I've always been under the assumption that C/C++ were faster or at least comparable to C#.net. What exactly is causing the C to run over 30 times slower?</p> <p>EDIT: It does appear that the C# optimizer was removing the root as it wasn't being used. I changed the root assignment to root += and printed out the total at the end. I've also compiled the C using cl.exe with the /O2 flag set for max speed.</p> <p>The results are now: 3.75 seconds for the C 2.61 seconds for the C#</p> <p>The C is still taking longer, but this is acceptable</p>

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