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This article (from http://www.codeproject.com/useritems/dynamicinvokedll.asp) demonstrates how to call an unmanaged MFC dll function from a C# code. Code using Reflection namespace. To use code snippets below you must add following.
using System.Reflection.Emit;
using System.Reflection;
Imagine you have a MFC dll (getmyversion.dll) with function named int GetDllversion(char* verstr) which returns your dll's version in verstr.
Below function creates a dynamic assembly object. And using DefinePInvokeMethod method creates a method which we will use it to access our dll function. To complete our global ops for our dynamic module call CreateGlobalFunctions. Using GetMethod function of our previously created method we can invoke our mfc dll funtion.
public object DynamicDllFunctionInvoke( string DllPath, string EntryPoint )
{
// Version string definition
byte[] verstr = new byte[1024];
//Define return type of your dll function.
Type returnType = typeof(int);
//out or in parameters of your function.
Type [] parameterTypes = {typeof(byte[])};
object[] parameterValues = {verstr};
string entryPoint = entrypoint;
// Create a dynamic assembly and a dynamic module
AssemblyName asmName = new AssemblyName();
asmName.Name = "tempDll";
AssemblyBuilder dynamicAsm =
AppDomain.CurrentDomain.DefineDynamicAssembly(asmName,
AssemblyBuilderAccess.Run);
ModuleBuilder dynamicMod =
dynamicAsm.DefineDynamicModule("tempModule");
// Dynamically construct a global PInvoke signature
// using the input information
MethodBuilder dynamicMethod = dynamicMod.DefinePInvokeMethod(
entryPoint, DllPath, MethodAttributes.Static | MethodAttributes.Public
| MethodAttributes.PinvokeImpl , CallingConventions.Standard,
returnType, parameterTypes, CallingConvention.Winapi,
CharSet.Ansi);
// This global method is now complete
dynamicMod.CreateGlobalFunctions();
// Get a MethodInfo for the PInvoke method
MethodInfo mi = dynamicMod.GetMethod(EntryPoint);
// Invoke the static method and return whatever it returns
object retval = mi.Invoke(null, parameterValues);
// Filled verstr paramter.
MessageBox.Show(System.Text.ASCIIEncoding.ASCII.GetString(verstr));
return retval;
}
Sample calling of the method is below.
DynamicDllFunctionInvoke(@"c:\getmyversion.dll","GetDllVersion");
calaquendi
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