DEV C++ compiler

Hi,

I used cygnus (or cygwin) before and now I'm using the DEV C++ to compile the files. I got a sth.c file which include the header file header.h and I use the DEV C++ to make a new project and add these two files into the project but still there is a compiling error until I put the header file in the same folder as the sth.c file. Is that necessary? Do we have to do that everytime we include header files? Coz one might include a lot of library files and it's hard to imagine how to track them all and put them into the same folder.

Also I have another problem now, which is the use of " S_IRGRP" and " S_IROTH". Seems like the compiler doesn't recognized these two.
It says and So anyone has any idea at all?
Thanz!!