C# Signature:

[DllImport("kernel32.dll", CharSet=CharSet.Ansi, ExactSpelling=true)]
public static extern UIntPtr GetProcAddress(IntPtr hModule, string procName);

VB Signature:

Private Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As Integer, ByVal lpProcName As String) As Integer

C++ Signature:

[DllImport("KERNEL32.DLL", CharSet=CharSet::Ansi, EntryPoint="GetProcAddress", ExactSpelling=true)]
static IntPtr GetProcAddress(IntPtr hModule, String^ lpProcName);

User-Defined Types:

None.

Notes:

GetProcAddress only comes in an ANSI flavor, hence we help the runtime by telling it to always use ANSI when marshalling the string parameter. We also prevent the runtime looking for a non-existent GetProcAddressA, because the default for C# is to set ExactSpelling to false.

Tips & Tricks:

This API becomes a lot more interesting in .NET v2.0 because the System.Runtime.InteropServices.Marshal class gains a new API called GetDelegateForFunctionPointer(). This means that you will be able to write code like this:

internal static class UnsafeNativeMethods {
   [DllImport("kernel32.dll", CharSet=CharSet.Ansi, ExactSpelling=true, SetLastError=true)]
   internal static extern IntPtr GetProcAddress(IntPtr hModule, string procName );
}

internal delegate int DllRegisterServerInvoker();

// code snippet in a method somewhere, error checking omitted
IntPtr fptr = UnsafeNativeMethods.GetProcAddress( hModule, "DllRegisterServer" );
DllRegisterServerInvoker drs = (DllRegisterServerInvoker) Marshal.GetDelegateForFunctionPointer( fptr, typeof(DllRegisterServerInvoker) );
drs(); // call via a function pointer

Sample Code:

tatic HMODULE hDLL;

typedef HRESULT (STDAPICALLTYPE * LPFNTEST) (void);

LPFNTEST _pfnTest;

hDLL = LoadLibrary("MyDLL.dll");

_pfnTest = (LPFNTEST)::GetProcAddress(hDLL, "Test");

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