我经常在运算符重载定义中看到哪些引用? [英] What do I often see references in operator overloading definitions?

问题描述

例如，在OGRE3D引擎中，我经常看到类似的东西

For example, in the OGRE3D engine, I often see things like

class_name class_name :: operator + (class_name & object)

代替

class_name class_name :: operator + (class_name object)

不是我更喜欢第二种形式，但是在输入中使用引用是否有特定的原因?是否有特殊情况需要使用引用而不是按值复制?还是性能问题?

Well it's not that I prefer the second form, but is there a particular reason to use a reference in the input ? Does it has special cases where it is necessary to use a reference instead of a copy-by-value ? Or is a performance matter ?

推荐答案

这是性能问题.通常，按引用传递要比按值传递便宜(它基本上等效于按指针传递).

It's a performance issue. Passing by reference will generally be cheaper than passing by value (it's basically equivalent to passing by pointer).

在不相关的注释上，您可能希望operator+的参数为const class_name &object.

On an unrelated note, you probably want the argument to operator+ to be const class_name &object.

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