为了避免重复包含头文件的问题,通常会使用包含保护(include guards)或 #pragma once。如果头文件没有这些保护机制,重复包含可能会导致重定义错误。 // 包含保护示例 #ifndef MY_HEADER_H #define MY_HEADER_H // 头文件内容 #endif // 或者使用 #pragma once #pragma once // 头文件内容 2.0 include-what-...
#pragma once: The #pragma once directive has a very simple concept. The header file containing this directive is included only once even if the programmer includes it multiple times during acompilation. This is not included in any ISO C++ standard. This directive works similar to the #include ...
} 【说明】:#pragma once并不是C++标准规定的,但是很多编译器都支持它。In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation. Thus, #pragma once...
} 【说明】:#pragma once并不是C++标准规定的,但是很多编译器都支持它。In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation. Thus, #pragma once...
【说明】：#pragma once并不是C++标准规定的，但是很多编译器都⽀持它。In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation. Thus, #pragma ...
This may seem like small issue but considering it is first impression a modern C++ programmer might face when starting vscode I think it important. If you create new file, save as main.h and type the line #pragma once followed by enter k...
the include guard idiom and#pragma oncein the same file. The compiler recognizes the include guard idiom, and implements the multiple-include optimization the same way as the#pragma oncedirective if no non-comment code or preprocessor directive comes before or after the standard form of the ...
#pragmaonce pragma oncelui-même n’est pas standard. Cela signifie que certains compilateurs ne le prendront pas en charge et, en raison de sa mise en œuvre complexe, il se peut qu’il ne soit pas toujours fiable. Cependant, il est très couramment pris en charge ; donc dans ...
一直以为#pragma once只在VC中支持=_=,所以项目里头文件用的都是#ifndef直到今天翻C++11的书的时候,看到“在C/C++标准中,#pragma 是一条预处理的指令………定义了以下语句 #pragma once……”这句话,才知道#pragma once貌似是符合标准的。。。使用VS2015,TDM-GCC 5.1 ,GCC(Ubuntu) 4.8 都能通过编译。。然...
It isn't part of the C++ Standard, but it's implemented portably by several common compilers.There's no advantage to use of both the include guard idiom and #pragma once in the same file. The compiler recognizes the include guard idiom, and implements the multiple-include optimization the ...