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Article : Tlbexp .exe and Regasm.exe (.Net FrameWork Tools Series)

Hey Guys,

TlbExp.exe and Regasm.exe tools aid us in exporting assembly information to
a type library so that non .Net Applications or unmanaged code use this type
library information to call .Net assembly.

Just like tlbimp which works on the entire COM Component (check out
yesterdays article) tlbexp also works on the entire assembly.

The entire assembly is converted at the same time. You cannot use it to
generate type information for a subset of the types.

Tbexp only generates the type library information for an assembly but it
does not register the type libraries unlike regasm.exe

Let us now create an assembly for which we will create a type library and
use it through Visual Basic.

1) Open a new dotnet project (Class Library).
2) Add a class to the project called MyClass as below.

public class MyClass
public MyClass()
public int Add (int i , int j)
return i +j;
public int Mul (int i , int j)
return i *j;

3) Strong name your assembly, Compile the project and create the assembly.
4) Go to the visual studio command prompt and type tlbexp /? to explore all
the options. I have enlisted them here
/out:FileName File name of type library to be produced
/nologo Prevents TlbExp from displaying logo
/silent Prevents TlbExp from displaying success
/verbose Displays extra information
/names:FileName A file in which each line specifies the captialization
of a name in the type library.
/? or /help Display this usage message

5) To create a typelibrary from it type the following command tlbexp
<application name>.dll e.g. tlbexp tlbexp.dll
6) If it the export was successful a success message diplaying you the
entire path and the name of the .tlb will be shown to you.

Assembly exported to F:\Net\tlbexp\bin\Debug\tlbexp.tlb

7) You can also use the /verbose option to check out the details of the
classes that were exported.
8) Although our typelibrary is created our assembly is not yet registered.
You can register the assembly using regasm tool.
9) Go to visual studio command prompt and type regasm /? to explore all the
options. I have enlisted them here

/unregister Unregister types
/tlb[:FileName] Export the assembly to the specified type library
and register it
/regfile[:FileName] Generate a reg file with the specified name instead
of registering the types. This option cannot be used with
the /u or /tlb options
/codebase Set the code base in the registry
/registered Only refer to already registered type libraries
/nologo Prevents RegAsm from displaying logo
/silent Silent mode. Prevents displaying of success
/verbose Displays extra information
/? or /help Display this usage message

10) To only register the assembly use the following command
regasm <application name>.dll e.g. regasm TlbExp.dll
11) You can also create a ,reg file containing all the registry entries
regasm TlbExp.dll /regfile:myTlbExp.dll .reg
12) You also create typelibrary from assembly using regasm tool by using
/tlb option.

13) To use this component from VB 6.0 put the assembly in GAC. You can do
this by either using gacutil or just drag and drop the assembly in
<drive>/winnt/assembly folder.

14) You can now use this assembly from VB 6.0 .
15) Open a VB std project. Go to references . Select the .tlb file that we
generated from the list.
16) Yes you can now use your .Net assembly from VB 6.0 :).

Sample code of using your .NET assembly from VB

Dim tlbExp As tlbExp.MyClass
Set tlbExp = New tlbExp.MyClass
Label1.Caption = tlbExp.Add(1, 2)

Note : You cannot use tlbexp on an assembly produced by tlbimp coz in that
case u can directly use type library which was used to produce the

-- Please post your queries and comments for my articles in the usergroup
for the benefit of all. I hope this step from my end is helpful to all of

Namratha (Nasha)

Nov 17 '05 #1
0 1491

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