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Error: 'Cannot open source file "XXXXX.hpp"' but app still building and working!

asked 2014-09-11 10:25:22 -0500

Doombot gravatar image

updated 2014-09-11 13:13:30 -0500

So I installed OpenCV 2.4.9 on a new computer and followed the various steps to link it's dll/lib in Visual Studio 2012 C++, as provided in the doc.

Using the sample code in the doc (copy/paste), the #include "opencv2\highgui\highgui.hpp" and all others opencv related includes are underlined in red, as well as every mention of opencv function/vars in the code. The error provided is "Cannot open source file "XXXXXXX.hpp", which is strange since I followed all the steps (even replacing the version number of the libs).

Stranger is that I compile and no error, run the example program from the command line and it works correctly.

So I started a new solution and tried to build another sample program. Again, same error in the IDE and the program builds just fine.

Anyone ever had a similar problem? In the past, when this kind of error happened, I was simply unable to build the app.

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Maybe the compiler is more forgiving or searching more agressive than Visual Studio. This is most likely a include path setting not (correctly) set in VS.

boaz001 gravatar imageboaz001 ( 2014-09-12 02:24:39 -0500 )edit

True, the problem was from the path. I will answer below

Doombot gravatar imageDoombot ( 2014-09-12 08:57:16 -0500 )edit

I will answer as soon as possible. The short answer is I used %OPENCV_DIR% (the Windows way) in my path setting of Visual Studio instead of $(OPENCV_DIR) or %(OPENCV_DIR). I assume that when Windows executed the program, it just saw %OPENCV_DIR% and knew what it meant, while Intellisense just could not understand.

Doombot gravatar imageDoombot ( 2014-09-12 09:02:37 -0500 )edit

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answered 2014-09-15 08:03:54 -0500

Doombot gravatar image

OK, I thought about it and found the culprit:

I am using a Windows Environment Variable, namely %OPENCV_DIR% , in my linkers/include pathway in Visual Studio. It appears that while this "syntax" (%VAR_NAME%) is correct in Windows itself, Visual Studio 2012 requires one of the following syntax (complete explanation of the syntax on

Global macros Applies to all items in a project configuration. Has the syntax $(name).


Item macros Has the syntax %(name). For a file, an item macro applies only to that file.


So, Visual Studio could not find the include header because to him, %OPENCV_DIR%\folder1\file1.hpp was simply a regular pathway.

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HYPOTHESIS: Somehow, since the program uses a .dll , it seems that during its execution, Windows could find the correct path to the folder because %OPENCV_DIR%\folder1\file1.hpp was "understandable".

Doombot gravatar imageDoombot ( 2014-09-15 08:04:27 -0500 )edit
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Asked: 2014-09-11 10:25:22 -0500

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Last updated: Sep 15 '14