C++ include and redefinition of class error

Question

I am currently programming a program which searches song according to diffrent parameters. In my system there are 2 types of songs: lyric and instrumetal. Since i need to p

Answer 1

As already answered, I would also use #pragma once, it is more convenient and clean. But be aware that it is not a C++ standard, so it can be a problem if you have to use different compilers (although it is a wide-spread extension).

Answer 2

You have to tell preprocessor to include your header files only once. You can achieve by adding #pragma once on the top of all *.h files:

#pragma once

//Your header file's code

It is also a good practice to always begin header files with this line.

Answer 3

They both include 'Song.h' file and preprocessor takes the file content twice. You need to write 'LyricsSong.h' and 'InstrumentalSong.h' file contents inside #ifndef #define and #endif directives. Like this

#ifndef LYRICS_SONG_H
#define LYRICS_SONG_H

your code goes here.
...

#endif