c++ header files including each other mutually

Question

I have two classes both defined in separate header files. Each file has a field that is type of other class. Now I included in header of each file the header of other file,

Answer 1

You shouldn't include the header files inside the other ones, just include the header files in your source files.

In the headers you can use a forward declaration:

// In Class1.h
class Class2;

// In class2.h
class Class1;

Also you can protect against a file being included twice using the preprocessor:

// Class1.h
#ifndef __CLASS_1_H
#define __CLASS_1_H

// content

#endif