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/EXPORT (Exports a Function)

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Exports a function by name or ordinal, or data, from your program.

Syntax

/EXPORT:entryname[,@ordinal[,NONAME]][,DATA]

Remarks

The /EXPORT option specifies a function or data item to export from your program so that other programs can call the function or use the data. Exports are usually defined in a DLL.

The entryname is the name of the function or data item as it is to be used by the calling program. ordinal specifies an index into the exports table in the range 1 through 65,535; if you do not specify ordinal, LINK assigns one. The NONAME keyword exports the function only as an ordinal, without an entryname.

The DATA keyword specifies that the exported item is a data item. The data item in the client program must be declared using extern __declspec(dllimport).

There are four methods for exporting a definition, listed in recommended order of use:

  1. __declspec(dllexport) in the source code

  2. An EXPORTS statement in a .def file

  3. An /EXPORT specification in a LINK command

  4. A comment directive in the source code, of the form #pragma comment(linker, "/export: definition ").

All these methods can be used in the same program. When LINK builds a program that contains exports, it also creates an import library, unless an .exp file is used in the build.

LINK uses decorated forms of identifiers. The compiler decorates an identifier when it creates the .obj file. If entryname is specified to the linker in its undecorated form (as it appears in the source code), LINK attempts to match the name. If it cannot find a unique match, LINK issues an error message. Use the DUMPBIN tool to get the decorated name form of an identifier when you need to specify it to the linker.

Note

Do not specify the decorated form of C identifiers that are declared __cdecl or __stdcall.

If you need to export an undecorated function name, and have different exports depending on the build configuration (for example, in 32-bit or 64-bit builds), you can use different DEF files for each configuration. (Preprocessor conditional directives are not allowed in DEF files.) As an alternative, you can use a #pragma comment directive before a function declaration as shown here, where PlainFuncName is the undecorated name, and _PlainFuncName@4 is the decorated name of the function:

#pragma comment(linker, "/export:PlainFuncName=_PlainFuncName@4")
BOOL CALLBACK PlainFuncName( Things * lpParams)

To set this linker option in the Visual Studio development environment

  1. Open the project's Property Pages dialog box. For details, see Set C++ compiler and build properties in Visual Studio.

  2. Select the Configuration Properties > Linker > Command Line property page.

  3. Enter the option into the Additional Options box.

To set this linker option programmatically

See also

MSVC linker reference
MSVC Linker Options