C语言中一元加(+)运算符的作用是什么? [英] What is the purpose of the unary plus (+) operator in C?

问题描述

在C语言中，编写类似以下内容是合法的:

In C, it's legal to write something like:

int foo = +4;

但是，据我所知，+4中的一元加号(+)是空操作.是吗?

However, as far as I can tell, the unary plus (+) in +4 is a no-op. Is it?

推荐答案

按照6.3.3.3中的C90标准:

As per the C90 standard in 6.3.3.3:

一元+运算符的结果是其操作数的值.整体提升是 在操作数上执行.结果为提升类型.

The result of the unary + operator is the value of its operand. The integral promotion is performed on the operand. and the result has the promoted type.

和

一元+或-运算符的操作数应具有算术类型.

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