C++ Interop is for the Performance Minded Developer

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace CSharpCon
{
 using CppMixed;

 class Program
 {
  [DllImport("Kernel32.dll")]
  private static extern bool QueryPerformanceCounter(out long lpPerformanceCount);

  [DllImport("Kernel32.dll")]
  private static extern bool QueryPerformanceFrequency(out long lpFrequency);

  [DllImport("CppMixed.dll")]
  private static extern void funcCalc (out int count, out double answer, out double mean);

  [DllImport("CppMixed.dll", SetLastError = true, CharSet = CharSet.Auto)]
  private static extern void funcInfo([MarshalAs(UnmanagedType.LPStr)]StringBuilder lpBuffer, out int cnt);


  static double ManagedManaged(int loop)
  {
   long start, stop, freq;
  
   QueryPerformanceFrequency(out freq);
   QueryPerformanceCounter(out start);

   for (int z = 0; z < loop; z++)
   {
    Simple sim = new Simple();
    Results res = new Results();

    sim.calc(res);
    //Console.WriteLine("Simple calc time {0}", time);
    //Console.WriteLine("Count = {0} Sum = {1}  Mean = {2}", res._count, res._answer, res._mean);
   }

   QueryPerformanceCounter(out stop);
   double time = (double)(stop - start) / (double)freq;

   return time;
  }
  static double NonBlitManaged(int loop)
  {
   long start, stop, freq;

   QueryPerformanceFrequency(out freq);
   QueryPerformanceCounter(out start);

   for (int z = 0; z < loop; z++)
   {
    Simple sim = new Simple();
    NonBlittable nb = new NonBlittable();

    sim.getTextDescription(nb);
    //Console.WriteLine("String {0} ; Length = {1}", nb._name, nb._len);
   }

   QueryPerformanceCounter(out stop);
   double time = (double)(stop - start) / (double)freq;
   
   return time;
  }

  static double NonBlitUnmanaged(int loop)
  {
   long start, stop, freq;

   QueryPerformanceFrequency(out freq);
   QueryPerformanceCounter(out start);

   for (int z = 0; z < loop; z++)
   {
    int c = 100;
    StringBuilder s = new StringBuilder(c);
    funcInfo(s, out c);
    
    //Console.WriteLine("String = {0} ,Len = {1}", s, c);
   }

   QueryPerformanceCounter(out stop);
   double time = (double)(stop - start) / (double)freq;
   
   return time;
  }
  static double ManagedUnmanaged(int loop)
  {
   long start, stop, freq;
  
   QueryPerformanceFrequency(out freq);
   QueryPerformanceCounter(out start);

   for (int z = 0; z < loop; z++)
   {
    int nCount = 0;
    double dblAns = 0.0, dblMean = 0.0;

    funcCalc(out nCount, out dblAns, out dblMean);

    //Console.WriteLine("C Function calc time {0}", time);
    //Console.WriteLine("Count = {0} Sum = {1}  Mean = {2}", nCount, dblAns, dblMean);
   }

   QueryPerformanceCounter(out stop);
   double time = (double)(stop - start) / (double)freq;

   return time;
  }

  static void Main(string[] args)
  {
   int glbLoop = 1;
   if (args.Length > 0)
     glbLoop = Convert.ToInt32(args[0]);

   Console.WriteLine("Number of call iterations equals {0}", glbLoop);
   Console.WriteLine(""); 

   int loop = 10;

   // The data returned by both functions are blittable data types.
   // The C# data is returned through a ref class whereas the C function returns
   // results via func parameter references
   Console.WriteLine("Blittable data types");
   Console.WriteLine("Reference class calc time, C-Func calc time");
    
   for (int x = 0; x < loop; x++)
   {
    /////////////////////////////////////////////////////
    // calling a Managed object from the mixed mode DLL
    double mmtime = ManagedManaged(glbLoop);

    ////////////////////////////////////////////////////
    // calling native C function using P/Invoke
    double mutime = ManagedUnmanaged(glbLoop);

    Console.WriteLine("{0}, {1}", mmtime, mutime);
   }
   Console.WriteLine("");
   
   //////////////////////////////////////////////////////////////////
   // communicating data via a structure with non-blittable types
   Console.WriteLine("Non-blittable data types");
   Console.WriteLine("Reference class calc time, C-Func calc time");

   for (int x = 0; x < loop; x++)
   {
    /////////////////////////////////////////////////////
    // calling a Managed object from the mixed mode DLL
    double nbmtime = NonBlitManaged(glbLoop);

    ////////////////////////////////////////////////////
    // calling native C function using P/Invoke
    double nbutime = NonBlitUnmanaged(glbLoop);

    Console.WriteLine("{0}, {1}", nbmtime, nbutime);
   }
   Console.WriteLine("");

  }
 }
}