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Dynamically loading a DLL - MC++

, 27 May 2002
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Shows how you can load an assembly at run time, instantiate a class in that assembly and call methods on the class


Today someone was asking how he can load a DLL dynamically with .NET. For some design related reasons he didn't want to add a reference to the DLL at compile time. For all I know this might be something everyone knew about except this particular individual and me. But I didn't know anything about this and I had never thought that anyone would want to do anything like that. Anyway as I found out it was really easy. This example is completely in MC++. Just in case someone starts flaming me saying this is an oft-discussed topic, I can always claim this is the first MC++ example. And my google searches kept directing me to pages that talked about normal dynamic loading of DLLs [means the non-.NET stuff]


Create a simple class library called Abc.dll. This will be the DLL which we will load dynamically.

#include "stdafx.h"

#using <mscorlib.dll>

using namespace System;

namespace Abc
    public __gc class Class1
        //This simply prefixes a Hello
        //to whatever string is passed
        String* Hello(String* str)
            return String::Concat(S"Hello ",str);

The Program

Okay, this is the little program that will load the above DLL, and call the Hello function, passing a string to it and also getting back the string that the function returns. Remember that Abc.dll must be in the same directory as our program's executable. I believe there are ways to put the DLL in some special directories that all .NET programs look into, but I am totally ignorant of such things.

#include "stdafx.h"

#using <mscorlib.dll>

using namespace System;
using namespace System::Reflection;

int wmain(void)
    //First we load our assembly
    //using the display name
    Assembly *a = Assembly::Load("Abc");

    //Now we get the type of the object
    //we want to instantiate. Since our class is
    //part of the assembly we have to use the full
    //name of the class with assembly name
    Type *t = a->GetType("Abc.Class1");

    //The MethodInfo class is used to
    //describe a method. It holds metadata about
    //a particular method. We get the MethodInfo for
    //our Hello method    
    MethodInfo *mi = t->GetMethod("Hello");    
    //Just showing off some public properties
    Console::WriteLine("Return type of *{0}* method is *{1}*",

    //We create an instance of our object.
    //Here the default constructor is called.
    Object *o = Activator::CreateInstance(t);

    //Prepare our argument list
    String *args[] = new String*[1]; 
    args[0]= S"Nish";  
    //We use Invoke to call the Hello method
    //on the object we got from CreateInstance above
    //We pass to it our arguments as an Object array
    String *s1=static_cast<String*>(mi->Invoke(o,args));
    return 0;


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About the Author

Nish Nishant
United States United States
Nish Nishant is a Software Architect/Consultant based out of Columbus, Ohio. He has over 16 years of software industry experience in various roles including Lead Software Architect, Principal Software Engineer, and Product Manager. Nish is a recipient of the annual Microsoft Visual C++ MVP Award since 2002 (14 consecutive awards as of 2015).

Nish is an industry acknowledged expert in the Microsoft technology stack. He authored
C++/CLI in Action for Manning Publications in 2005, and had previously co-authored
Extending MFC Applications with the .NET Framework for Addison Wesley in 2003. In addition, he has over 140 published technology articles on and another 250+ blog articles on his
WordPress blog. Nish is vastly experienced in team management, mentoring teams, and directing all stages of software development.

Contact Nish : You can reach Nish on his google email id voidnish.

Website and Blog

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Comments and Discussions

GeneralUsing OpenGL and GNU in Visual C++.NET (2002) Pin
Sctt H. Chang21-Aug-03 5:21
memberSctt H. Chang21-Aug-03 5:21 
GeneralRe: Using OpenGL and GNU in Visual C++.NET (2002) Pin
Ffelagund1-Mar-04 10:30
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