The normal way to set up a program that uses a class is to have three
files: the class header file with a .h extension, a class
implementation file with a .cpp extension, and a program
file also with a .cpp.
The program file has a #include for the class header file,
and the program and class are linked by compiling them together. The
set up looks like this example:
FooClass.h FooClass.cpp Program.cpp
----------- --------------------- ---------------------
class Foo { #include "FooClass.h" #include "FooClass.h"
.... .... int main(void) {
.... .... Foo AFooInstance;
.... .... ....
}; .... }
----------- --------------------- ---------------------
prompt> g++ Program.cpp FooClass.cpp -o Program
Unfortunately, g++ does not cope easily with templates when
a template class is declared in one file and an instance of the class is
defined in another.
The easiest way to overcome this is to include the class implementation
file in the program file, and compile just the program file. The set
up looks like this exmaple:
FooTClass.h FooTClass.cpp Program.cpp
------------------ ---------------------- ------------------------
template <class T> #include "FooTClass.h" #include "FooTClass.cpp"
class FooT { .... int main(void) {
.... .... FooT<int> AFooTInt;
.... .... ....
}; .... }
------------------ ---------------------- ------------------------
prompt> g++ Program.cpp -o Program