National Instruments 320685D-01 ユーザーズマニュアル

Chapter 3

Windows 95/NT Compiler/Linker Issues

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 National Instruments Corporation

3-5

LabWindows/CVI Programmer Reference Manual

When installing LabWindows/CVI, you must choose your compatible compiler. If you want 
to change your choice of compatible compiler later, you can run the installation program and 
change to another compatible compiler.

You can see which compatible compiler is active in LabWindows/CVI by selecting the 
Compiler Options command in the Options menu of the Project window.

If you create an object file, library file, or DLL import library in LabWindows/CVI, you can 
use the file only in the current compatible compiler or in a copy of LabWindows/CVI 
that you installed with the same compatibility choice. For detailed information on using 
LabWindows/CVI-generated object and static library files in external compilers, refer to 
the 

 section later in this chapter.

If you load an object file, library file, or DLL import library file in LabWindows/CVI, 
you must have created the file in the current compatible compiler or in a copy of 
LabWindows/CVI that you installed with the same compatibility choice. If you have 
a DLL but you do not have a compatible DLL import library, LabWindows/CVI reports an 
error when you attempt to link your project.

To create a compatible import library, you must have an include file that contains the 
declarations of all the functions and global variables you want to access from the DLL. 
Load the include file into a Source window, and select the Generate DLL Import Library 
command in the Options menu.

Make sure the calling conventions of the function declarations in the include file match the 
calling convention of the functions in the DLL. Whereas DLLs usually export functions with 
the 

__stdcall

 calling convention, the 

__stdcall

 keyword is sometimes missing from the 

function declarations in the associated include files. If you generate an import library from an 
include file that does not agree with the calling convention the DLL uses, you can successfully 
build a project that contains the import library, but LabWindows/CVI usually reports a general 
protection fault when you run the project.

In general, you can use a DLL without regard to the compiler you used to create it. Only the 
DLL import library must be created for the current compatible compiler. Some cases exist, 
however, in which you cannot call a DLL that you created using one compiler from an 
executable or DLL that you created using another compiler. If you want to create DLLs that 
you can use in different compilers, design the Application Programming Interface (API) for 
your DLL to avoid such problems. The following are areas in which the DLLs that external 
compilers create are not fully compatible.

00ProRef.book : 06chap03.fm  Page 5  Monday, March 9, 1998  3:23 PM