Shulou(Shulou.com)06/03 Report--

For gadgets, it is estimated that there are only a few files written in C++, and there are few compilation errors caused by the mutual inclusion of design header files.

However, as the software functions become more and more complex, and the call relationship between the modules becomes less and less obvious, it is very likely that the A header file contains the B header file and the B header file contains the A header file. this mutual inclusion of header files can lead to errors in which the compilation type cannot be found.

The simplest code is as follows:

A.h is as follows

# include "B.H" class A {B b;}

A.cpp is as follows

# include "A.H" class A {...}

B.H is as follows

# include "A.h" class B {AA;}

B.cpp is as follows

# include "B.H" class B {...}

If the file is in this case, the compilation cannot find the type, because A contains the B header file in the header file, and B contains the A header file, which can cause compilation errors.

Solution.

The solution is a pre-declaration.

The modified code is as follows

A.h is as follows

Class B _ class A {B _ b;}

A.cpp is as follows

# include "A.H" # include "B.H" class A {...}

B.H is as follows

Class Aclass B {An a;}

B.cpp is as follows

# include "B.H" # include "A.H" class B {...}

What if you want to do it once and for all?

For the header files of frequently used modules, you can write a unified pre-declaration file, write all the commonly used declarations into the header file, such as includeDeclare.h, and then put the actual header files into a file, such as includeHeaders.h. So when you use it in other places later, just introduce includeDeclare.h in the header file and includeHeaders.h in the implementation cpp file.

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