Where does Visual Studio look for C++ header files?

I checked out a copy of a C++ application from SourceForge (HoboCopy, if you're curious) and tried to compile it.

Visual Studio tells me that it can't find a particular header file. I found the file in the source tree, but where do I need to put it, so that it will be found when compiling?

Are there special directories?

Visual Studio looks for headers in this order:

• In the current source directory.
• In the Additional Include Directories in the project properties (Project -> [project name] Properties, under C/C++ | General).
• In the Visual Studio C++ Include directories under Tools → Options → Projects and Solutions → VC++ Directories.
• In new versions of Visual Studio (2015+) the above option is deprecated and a list of default include directories is available at Project Properties → Configuration → VC++ Directories

In your case, add the directory that the header is to the project properties (Project Properties → Configuration → C/C++ → General → Additional Include Directories).