Q: Header file inside the same solution http://youtu.be/6NCtnKcwOas (select better quality!)
As you can see on the attached video, I have the two projects in my solution - a dll creator and a simple testing project. Just followed this tutorial .
Why does the MathFuncsDll.h still remain undetected?Everything works fine after specifying the full path after '#include'. However, I don't want to use such rough-and-ready method because it looks messy and unprofessionally. 

A: If you can specify the file using an absolute path, but not by only using its filename, the compiler doesn't "know" about the folder containing that file.
You can tell the compiler about your additional include directories via the /I directive (documentation). And of course you can set that via the IDE.

