什么是用C一元“+”操作​​符的目的是什么？ [英] What is the purpose of the unary '+' operator in C?

问题描述

在C，是合法的写类似：

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

int foo = +4;

不过，据我所知道的，一元 + 在 +4 是一个空操作。是吗？

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

推荐答案

由于按照C90标准：

一元+运算符的结果就是它的操作数的价值。积分促销
  操作数执行。其结果具有推广的类型。

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

的操作数一元+或 - 操作员应算术类型 ..

The operand of the unary + or - operator shall have arithmetic type..

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