National Instruments 320685D-01 DLL Search Precedence

Chapter 4 Windows3.1 Compiler/Linker Issues

National Instruments Corporation 4-23 LabWindows/CVI Programmer Reference Manual

DLL Search Precedence

LabWindows/CVI finds a DLL file in the following ways for Windows3.1:

•If the .dll file is associated with a .fp file, LabWindows/CVI uses the following search

precedence to find the DLL.

1. If a .pth file with the same full path name as the .fp file is in the project,

LabWindows/CVI uses the standard Windows DLL search algorithm. The .pth

file must contain the name of the .dll file, such as mystuff.dll. It must

contain an absolute path or a simple filename.

2. If a .dll file with the same full path name as the .fp file is in the project,

LabWindows/CVI uses the absolute path of the .dll file in the projec t to lo ad

the .dll file.

3. If a .pth file with the same base name as the .fp file is in the same directory as

the .fp file and a .lib or .obj file of the same base name does not exist in the

same directory, LabWindows/CVI uses the standard Windows DLL search

algorithm. The .pth file must contain the name of the .dll file, such as

mystuff.dll. It must not contain any directory names or slashes.

4. If a .dll file with the same base name as the .fp file is in the same directory as

the .fp file, LabWindows/CVI loads the .dll file as long as no .lib, .obj,

or .pth file of the same base name appears in the same directory.

5. If a .pth or .dll file does not appear in the same directory as the .fp file,

LabWindows/CVI uses the standard Windows search algorithm to look for a

DLL with the same base name as the .fp file. Thus, if a DLL with the same base

name is in the windows or windows\system directory or a directory listed in

your PATH environment variable, LabWindows/CVI finds it.

DLLs for VXIplug&play drivers are not in the same directory as the .fp files, but the

directory that contains the DLL is listed in the PATH environment variable. Therefore,

Step 5 makes it easier for you to use VXIplug&play instrument driver DLLs in

LabWindows/CVI for Windows3.1.

•If the .dll file is not associated with a .fp file, LabWindows/CVI uses the following

search precedence to find the DLL:

1. If a .pth file is in the project list, LabWindows/CVI uses the standard Windows

DLL search algorithm. The .pth file must contain the name of the .dll file,

such as mystuff.dll. It must contain an absolute path or a simple filename.

2. If the .dll file is in the project list, then LabWindows/CVI uses the absolute

pathname to find the .dll file.