How do you begin a page of C plus plus coding?

Answer 1

It depends whether you are writing a header or a source file. Generally you will begin with the header, and this should always begin with a header guard:

// file: my_header.hpp

#ifndef _MY_HEADER_HPP_

#define _MY_HEADER_HPP_

//...

// header code goes here

// ...

#endif _MY_HEADER_HPP_

Although the opening header guard should always be placed first, it's a good idea to precede the header guard with a multi-line comment briefly explaining the purpose of the header and its contents, as well as the author's contact details and any required copyright notifications.

The header code will include any other required headers as well as any required forward declarations, followed by its own declarations. You may also include definitions for those declarations, however its generally best to keep implementation details separate from the declarations. The only exceptions are when declaring class templates, which must be completely defined in the header, or when defining implicit inline functions.

The corresponding source file must include the header file, along with any other header files for its forward declarations, before defining the implementations of the header's undefined declarations. Other files that require those definitions need only include the corresponding header file.