C和C之间的条件运算差异++ [英] Conditional operator differences between C and C++

问题描述

我读的地方，在：用C 运营商在C ++中略有不同，即有一些源$ C ​​$ C这两种语言的工作方式不同。不幸的是，我找不到任何地方的文本。有谁知道这有什么区别？

I read somewhere that the ?: operator in C is slightly different in C++, that there's some source code that works differently in both languages. Unfortunately, I can't find the text anywhere. Does anyone know what this difference is?

推荐答案

在C中的条件运算符++可以返回一个左值，而C不容许类似的功能。因此，以下是在C ++中合法的：

The conditional operator in C++ can return an lvalue, whereas C does not allow for similar functionality. Hence, the following is legal in C++:

(true ? a : b) = 1;

在C复制，你将不得不求助于的if / else，或直接处理引用：

To replicate this in C, you would have to resort to if/else, or deal with references directly:

*(true ? &a : &b) = 1;

此外，在C ++中，：和 = 运营商拥有的等于precedence和组从右到左的选择，例如：

Also in C++, ?: and = operators have equal precedence and group right-to-left, such that:

(true ? a = 1 : b = 2);

是有效的C ++ code，但会抛出C中的错误，而不绕前最后pression括号：

is valid C++ code, but will throw an error in C without parentheses around the last expression:

(true ? a = 1 : (b = 2));

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