C++之 头文件
浏览数：22 /
时间：2015年06月08日
bash:
g++ a.cpp b.cpp --save-temps -Wall
Definition of a class
- In C++,separated .h and .cpp files are used to define one class.
- Class declaration and prototypes in that class are in the header file(.h).
- All the bodies of these functions are in the source file(.cpp).
- If a function is declared in a header file,you must include the header file everywhere the function is used and where the function is defined.
- If a class is declared in a header file,you must include the header file everywhere the class is used and where class member functions are defined.
- The header is a contract between you and the user of your code.
- The compile enforces the contract by requirig you to declare all structures and functions before they are used.
Declarations vs. Definitions
- A .cpp file is a compile unit
- Only declaratons are allowed to be in .h
- extern variables
- function prototypes //函数原型
- class/struct declaration
- #include is to insert the included file into the .cpp file at where the #include statement is.
- #include "xx.h":first search in the current directory,then the directories declared somewhere
- #include <xx.h>:search in the specified directories
- #include <xx>:same as #include <xx.h>
#ifndef HEADER_FLAG#define HEADER_FLAG//Type declaration here...#endif // HEADER_FLAG
Tips for header
- One class declaration per header file
- Associated with one source file in the same prefix of file name.
- The contents of a header file is surrounded with #ifndef #define #endif
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