# Tlbexp.exe (Type Library Exporter)

The Type Library Exporter generates a type library that describes the types defined in a common language runtime assembly.

This tool is automatically installed with Visual Studio. To run the tool, use the Developer Command Prompt for Visual Studio (or the Visual Studio Command Prompt in Windows 7). For more information, see Command Prompts.

At the command prompt, type the following:

## Syntax

tlbexp assemblyName [options]


## Parameters

Argument Description
assemblyName The assembly for which to export a type library.
Option Description
/asmpath: directory Specifies the location to search for assemblies. If you use this option, you must explicitly specify the locations to search for referenced assemblies, including the current directory.

When you use the asmpath option, the Type Library Exporter will not look for an assembly in the global assembly cache (GAC).
/help Displays command syntax and options for the tool.
/names: filename Specifies the capitalization of names in a type library. The filename argument is a text file. Each line in the file specifies the capitalization of one name in the type library.
/nologo Suppresses the Microsoft startup banner display.
/oldnames Forces Tlbexp.exe to export decorated type names if there is a type name conflict. Note that this was the default behavior in versions prior to the .NET Framework version 2.0.
/out: file Specifies the name of the type library file to generate. If you omit this option, Tlbexp.exe generates a type library with the same name as the assembly (the actual assembly name, which might not necessarily be the same as the file containing the assembly) and a .tlb extension.
/silence: warningnumber Suppresses the display of the specified warning. This option cannot be used with /silent.
/silent Suppresses the display of success messages. This option cannot be used with /silence.
/tlbreference: typelibraryname Forces Tlbexp.exe to explicitly resolve type library references without consulting the registry. For example, if assembly B references assembly A, you can use this option to provide an explicit type library reference, rather than relying on the type library specified in the registry. Tlbexp.exe performs a version check to ensure that the type library version matches the assembly version; otherwise, it generates an error.

Note that the tlbreference option still consults the registry in cases where the ComImportAttribute attribute is applied to an interface that is then implemented by another type.
/tlbrefpath: path Fully qualified path to a referenced type library.
/win32 When compiling on a 64-bit computer, this option specifies that Tlbexp.exe generates a 32-bit type library.
/win64 When compiling on a 32-bit computer, this option specifies that Tlbexp.exe generates a 64-bit type library.
/verbose Specifies verbose mode; displays a list of any referenced assemblies for which a type library needs to be generated.
/? Displays command syntax and options for the tool.

Note

The command-line options for Tlbexp.exe are case-insensitive and can be supplied in any order. You only need to specify enough of the option to uniquely identify it. For example, /n is equivalent to /nologo, and /o: outfile.tlb is equivalent to /out: outfile.tlb.

## Remarks

Tlbexp.exe generates a type library that contains definitions of the types defined in the assembly. Applications such as Visual Basic 6.0 can use the generated type library to bind to the .NET types defined in the assembly.

Important

You cannot use Tlbexp.exe to export Windows metadata (.winmd) files. Exporting Windows Runtime assemblies is not supported.

The entire assembly is converted at once. You cannot use Tlbexp.exe to generate type information for a subset of the types defined in an assembly.

You cannot use Tlbexp.exe to produce a type library from an assembly that was imported using the Type Library Importer (Tlbimp.exe). Instead, you should refer to the original type library that was imported with Tlbimp.exe. You can export a type library from an assembly that references assemblies that were imported using Tlbimp.exe. See the examples section below.

Tlbexp.exe places generated type libraries in the current working directory or the directory specified for the output file. A single assembly might cause several type libraries to be generated.

Tlbexp.exe generates a type library but does not register it. This is in contrast to the Assembly Registration tool (Regasm.exe), which both generates and registers a type library. To generate and register a type library with COM, use Regasm.exe.

If you do not specify either the /win32 or /win64 option, Tlbexp.exe generates a 32-bit or 64-bit type library that corresponds to the type of computer on which you are performing the compilation (32-bit or 64-bit computer). For cross-compilation purposes, you can use the /win64 option on a 32-bit computer to generate a 64-bit type library and you can use the /win32 option on a 64-bit computer to generate a 32-bit type library. In 32-bit type libraries, the SYSKIND value is set to SYS_WIN32. In 64-bit type libraries, the SYSKIND value is set to SYS_WIN64. All data type transformations (for example, pointer-sized data types such as IntPtr and UIntPtr) are converted appropriately.

If you use the MarshalAsAttribute attribute to specify a SafeArraySubType value of VT_UNKOWN or VT_DISPATCH, Tlbexp.exe ignores any subsequent use of the SafeArrayUserDefinedSubType field. For example, given the following signatures:

[return:MarshalAs(UnmanagedType.SafeArray, SafeArraySubType=VarEnum.VT_UNKNOWN, SafeArrayUserDefinedSubType=typeof(ConsoleKeyInfo))] public Array StructUnkSafe(){return null;}
[return:MarshalAs(UnmanagedType.SafeArray, SafeArraySubType=VarEnum.VT_DISPATCH, SafeArrayUserDefinedSubType=typeof(ConsoleKeyInfo))] public Array StructDispSafe(){return null;}


the following type library is generated:

[id(0x60020004)]
HRESULT StructUnkSafe([out, retval] SAFEARRAY(IUnknown*)* pRetVal);
[id(0x60020005)]
HRESULT StructDispSafe([out, retval] SAFEARRAY(IDispatch*)* pRetVal);


Note that Tlbexp.exe ignores the SafeArrayUserDefinedSubType field.

Because type libraries cannot accommodate all the information found in assemblies, Tlbexp.exe might discard some data during the export process. For an explanation of the transformation process and identification of the source of each piece of information emitted to a type library, see the Assembly to Type Library Conversion Summary.

Note that the Type Library Exporter exports methods that have TypedReference parameters as VARIANT, even though the TypedReference object has no meaning in unmanaged code. When you export methods that have TypedReference parameters, the Type Library Exporter will not generate a warning or error and unmanaged code that uses the resulting type library will not run properly.

The Type Library Exporter is supported on Microsoft Windows 2000 and later.

## Examples

The following command generates a type library with the same name as the assembly found in myTest.dll.

tlbexp myTest.dll


The following command generates a type library with the name clipper.tlb.

tlbexp myTest.dll /out:clipper.tlb


The following example illustrates using Tlbexp.exe to export a type library from an assembly that references assemblies that were imported using Tlbimp.exe.

First use Tlbimp.exe to import the type library myLib.tlb and save it as myLib.dll.

tlbimp myLib.tlb /out:myLib.dll


The following command uses the C# compiler to compile the Sample.dll, which references myLib.dll created in the previous example.

CSC Sample.cs /reference:myLib.dll /out:Sample.dll


The following command generates a type library for Sample.dll that references myLib.dll.

tlbexp Sample.dll