You receive an LNK4197 error in the 64-bit version of the Visual C++ Compiler (835326)

The information in this article applies to:

Microsoft Windows Server 2003 Driver Development Kit (DDK)
the operating system: Microsoft Windows Server 2003, 64-Bit Enterprise Edition
the operating system: Microsoft Windows Server 2003, 64-Bit Datacenter Edition

SUMMARY

When you build a DLL by using the 64-bit version of the Microsoft Visual C++ Compiler and Linker, you may receive Linker error number LNK4197 if a function has been declared for export more than one time.

SYMPTOMS

The Linker output may be similar to the following:

C:\>link /NOLOGO /def:Sample.def /pdb:Sample.pdb /out:Sample.dll  Sample.obj
Sample.obj : warning LNK4197: export 'DllSample' specified multiple times; using first specification
   Creating library Sample.lib and object Sample.exp

CAUSE

The Linker error number LNK4197 is generated when a function has been declared for export more than one time. A function is declared for export in one of the following ways:

The function is declared by using the __declspec(dllexport) keyword in your C source file:
```
__declspec(dllexport) int DllSample() 
{
   return 42;
}
```
The function is declared by using a module-definition (.DEF) file:
```
EXPORTS
   DllSample
```

This Linker error may occur most frequently when both the __declspec(dllexport) keyword and a .DEF file are used to define the same function name in a .DLL project.

RESOLUTION

To resolve this behavior, define exported functions only one time, either by using the __declspec(dllexport) keyword or by using a .DEF file. Do not use both of these methods.

STATUS

This behavior is by design.

MORE INFORMATION

Declaring a function for export more than one time may not produce the Linker error that is described in the "Symptoms" section of this article in 32-bit versions of the Microsoft Windows C++ Compiler and Linker. However, Microsoft recommends that you define function exports only one time in both 32-bit and 64-bit versions of the Windows C++ Compiler and Linker.

Modification Type:	Major	Last Reviewed:	3/1/2004
Keywords:	kbDDK kbprb KB835326 kbAudDeveloper