What should go into an .h file?

Question

When dividing your code up into multiple files just what exactly should go into an .h file and what should go into a .cpp file?

Answer 1

the header file (.h) should be for declarations of classes, structs and its methods, prototypes, etc. The implementation of those objects are made in cpp.

in .h

    class Foo {
    int j;

    Foo();
    Foo(int)
    void DoSomething();
}