Until I realised that Geany didn’t compile both of the two .cpp files, and link them together.

When I manually compiled/linked them with g++ it worked just fine.

add(int x, int y)

to:

add(int x, int y)
{ return x + y: }

C:Dev-CppMakefile.win [Build Error] [Project1.exe] Error 1

ld returned 1 exit status

[Linker error] undefined reference to `add(int, int)’

I copied the add header and saved it as a .h file in the same directory as the project. Has anyone else had this error? How can I fix it?

Ideally, you should include your header file in every .cpp file in which you use the stuff it declares. However, in practice, since header files can include other header files, this may not be strictly necessary. For example, you might have a class named Foo that uses strings, so foo.h will include string.h. foo.cpp (which also uses strings) should ideally include both foo.h and string.h, but since foo.h already includes string.h, if you only include foo.h you will still be able to use strings.

So my question is the following: Should be include the header file for every source file (in this case I’m thinking about add.cpp or can we only use it for one source file. Also, isn’t it going to scream at us for “redefining?” the functions?

Edit: I just found out. The header guard prevent that from happenning. As for using it in all the source files makes it easier and saves times?

Excuse my english, it is not my native tongue. :P