1、尽量用const和inline而不用#define 这个条款最好称为：“尽量用编译器而不用预处理”，因为#define经常被认为好象不是语言本身的一部分。这是问题之一。2、再看下面的语句：define ASPECT_RATIO 1.653 编译器会永远也看不到ASPECT_RATIO这个符号名，因为在源码进入编译器之前，它会被预处理程...
由于头文件包含可以嵌套,那么C文件就有可能包含多次同一个头文件,就可能出现重复定义的问题的 通过条件编译开关来避免重复包含(重复定义) 例如 #ifndef __headerfileXXX__ #define __headerfileXXX__ … //文件内容 … #endif Instances[实例]: 1、防止一个头文件被重复包含 #ifndef COMDEF_H #define COMDEF...
If you want to use a class in multiple files, you should put the class definition in a header file and define the class methods in a corresponding source file. (You an also useinline functionsfor the methods.) If you want to use a variable in multiple files, you should put the declara...
It has to do with the way programs are compiled. Assume for the following each header file ends in .h, and each source file ends in .cpp. When you compile a single source file, it will take every .h and .cpp and litteraly paste it on the line#include "AwesomeClass.cppto produce ...
一旦包含了header，它会检查是否定义了一个唯一的值（在本例中是HEADERFILE_H），如果没有定义，它会...
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You could simply define a series ofconst intsin a header file: // Constants.h#if!defined(MYLIB_CONSTANTS_H)#defineMYLIB_CONSTANTS_H 1constinta =100;constintb =0x7f;#endif This works because in C++ a name at namespace scope (including the global namespace) that is explicitly declared ...
一旦包含了header，它会检查是否定义了一个唯一的值（在本例中是HEADERFILE_H），如果没有定义，它会...
7.头文件(.h)可以被头文件或C文件包含; 重复包含(重复定义) 由于头文件包含可以嵌套,那么C 文件就有可能包含多次同一个头文件,就可能出现重复定义的问题的 通过条件编译开关来避免重复包含(重复定义) 例如 #ifndef __headerfileXXX__ #define __headerfileXXX__ ...
This is just extra information, but if you really want the string in a header file, try something like: class foo { public: static const std::string& RECTANGLE(void) { static const std::string str = "rectangle"; return str; } }; Though I doubt that's recommended. Share...