C# Signatures:

[DllImport("oleaut32.dll")]
static extern int RegisterTypeLib(ITypeLib ptlib,
   [MarshalAs(UnmanagedType.BStr)] string szFullPath,
   [MarshalAs(UnmanagedType.BStr)] string szHelpDir);

[DllImport("oleaut32.dll", PreserveSig=false)]
static extern void RegisterTypeLib(ITypeLib ptlib,
   [MarshalAs(UnmanagedType.BStr)] string szFullPath,
   [MarshalAs(UnmanagedType.BStr)] string szHelpDir);

Possible VB Signatures:

Declare Function RegisterTypeLib Lib "oleaut32.dll" (TODO) As TODO   ???
Declare Function RegisterTypeLib Lib "oleaut32.dll" (ByRef ptlib As Runtime.InteropServices.ComTypes.ITypeLib, <[In](), MarshalAs(UnmanagedType.BStr)> ByRef szFullPath As String, <[In](), MarshalAs(UnmanagedType.BStr)> ByRef szHelpDir As String) As Integer

VB6 Signature:

Declare Function RegisterTypeLib Lib "oleaut32.dll" (ByVal pTLB As Object, szFullPath As Byte, szHelpFile As Byte) As Long

User-Defined Types:

For the ITypeLib parameter, you can use System.Runtime.InteropServices.UCOMITypeLib, already defined in mscorlib.dll. Note that in v2.0 (Whidbey) of the .NET Framework, this interface has been deprecated in favor of System.Runtime.InteropServices.ComTypes.ITypeLib.

Notes:

The first signature returns the raw HRESULT. The second signature throws an exception when a failure HRESULT is returned.

Tips & Tricks:

Please add some!

Sample Code:

Please add some!

Alternative Managed API:

Do you know one? Please contribute it!