C语言中#pragma和_Pragma()的区别 [英] Difference between #pragma and _Pragma() in C

问题描述

#pragma和_Pragma()在C语言中有什么区别?

What is the difference between #pragma and _Pragma() in C?

语法:

#pragma arg

和

_Pragma(arg)

什么时候应该使用 _Pragma(arg)?

推荐答案

_Pragma 运算符在 C99 中引入._Pragma(arg) 是一个运算符，很像 sizeof 或 defined，可以嵌入到宏中.

_Pragma operator introduced in C99. _Pragma(arg) is an operator, much like sizeof or defined, and can be embedded in a macro.

根据 cpp.gnu.org 参考:

它的语法是_Pragma (string-literal)，其中string-literal可以是普通的或宽字符的字符串文字.将所有 \ 替换为单个 并将所有 " 替换为 ". 然后处理结果，就好像它出现在 #pragma 指令的右侧一样.例如，

Its syntax is _Pragma (string-literal), where string-literal can be either a normal or wide-character string literal. It is destringized, by replacing all \ with a single and all " with a ". The result is then processed as if it had appeared as the right hand side of a #pragma directive. For example,

 _Pragma ("GCC dependency "parse.y"")

与#pragma GCC dependency "parse.y" 效果相同.使用宏也可以达到同样的效果，例如

has the same effect as #pragma GCC dependency "parse.y". The same effect could be achieved using macros, for example

 #define DO_PRAGMA(x) _Pragma (#x)
 DO_PRAGMA (GCC dependency "parse.y")

根据 IBM 教程:

_Pragma 运算符是指定#pragma 的另一种方法指令. 例如，以下两个语句是等价的:

The _Pragma operator is an alternative method of specifying #pragma directives. For example, the following two statements are equivalent:

#pragma comment(copyright, "IBM 2010")
_Pragma("comment(copyright, "IBM 2010")")

字符串 IBM 2010 被插入到 C++ 目标文件中，当编译如下代码:

The string IBM 2010 is inserted into the C++ object file when the following code is compiled:

_Pragma("comment(copyright, "IBM 2010")")
int main() 
{
   return 0;
}

有关_pragma 举个例子.

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