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

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Article ID: 835326 - View products that this article applies to.
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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.

Properties

Article ID: 835326 - Last Review: March 1, 2004 - Revision: 1.1
APPLIES TO
  • Microsoft Windows Server 2003 Driver Development Kit (DDK)
  • Microsoft Windows Server 2003, Enterprise x64 Edition
  • Microsoft Windows Server 2003, Datacenter x64 Edition
Keywords: 
kbddk kbprb KB835326

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