VS2003 can't find .h file even after addition to "additional incl. dirs"

I have file which needs to include blah.h in another project. I've tried adding the director开发者_高级运维y that holds the blah.h file to

Project -> Project Properties -> Additional include directories

but I keep getting a "C1083: Cannot open include file: blah.h: No such file or directory". I've tried absolute and relative paths to the folder housing blah.h with no success.

I'm using Visual Studios 2003. and my include statement looks like

#include "blah.h"

Any suggestions?

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Get the build (or at least this part of the build) working using:

#include "c:/path/to/blah.h"

If/when VS stops complaining about not being able to find blah.h, cut-n-paste the path used in the #include into the "Additional include directories". Remember that the "Additional include directories" field should have the directories separated by a semi-colon.

Also, make sure that you set the "Additional include directories" property for all appropriate build configurations and platforms (drop-downs at the top of the Project property page dialog). Since the dialog opens up with only the "Active" configuration selected, I often find myself setting up an option for only the "Debug"/"Win32" configuration, then wonder for a second what's gone wrong when I get errors after switching to the "Release" configuration or "x64".

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For problems like this I use ProcessMonitor, a free utility from Microsoft. Among other things, it logs accesses to files. Filter on blah.h, see what path Visual Studio is really using, then adjust your "Additional Includes" as needed.

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Ok here was my problem and the solution I came up with:

I have a multi-project solution in VS2003. In one project I have a templated class Child defined in Bar.h which inherits from a non-templated class Parent in Foo.h. Parent has a static member some_mutex declared in it. This meant that I needed to define some_mutex in Foo.cpp.

The problem arose when I tried to include Bar.h in files in other projects, e.g. other.vcproj. Without adding the include path to Bar.h in other.vcproj I'd get a C1083 error because the compiler couldn't find the definition for Child. But when I added Bar.h's include path to other.vcproj I'd get a LNK2001 error for some_mutex because Foo.cpp was in a different project and was not getting included/compiled. This meant that some_mutex was undefined and that caused the LNK2001 error.

The solution was to put Foo.h, Foo.cpp, and Bar.h in their own project NewProj and create a static library. The other projects that wanted to use the class Child just needed to include NewProj.lib, add the path to NewProj.lib, and add the include path to Bar.h.

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If you have entered the path to the "blah.h" directory as a relative path, be aware that VS2008 interprets those paths relative to the directory holding the .vcproj project file. So you'll need to work out what that would be.

If your C++ file is "C:\myprogram\source\foo.cpp" and your include file is "C:\myprogram\includes\blah.h", it is not adequate to provide an include path of "..\includes". You have to figure out where your project file is. If it's "C:\myprogram\build\mysolution\myprogram\myprogram.vcproj" then the include path must be "..\..\..\includes".