是通过引用来传递常量而不是非常量传递引用更好? [英] Is is better to do const pass by references over non-const pass by references?

问题描述

我遇到了这个.

http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Reference_Arguments#Reference_Arguments

根据样式指南，只允许 const 引用作为参数.(我是这么理解的)

According to the style guide, only const references are allowed as parameters. (That's what I understood)

虽然，我似乎不喜欢这种方法.

Although, I don't seem to like that approach.

评论?

推荐答案

以下是几条经验法则，可用于在您的选择之间做出决定:

Here are a couple of rules of thumb that can be useful when deciding between your options:

如果您不需要修改传入函数的对象，请考虑对象的大小是否小于或等于指针的大小.如果是，则按值传递；否则，通过常量引用.

If you don't need to modify the object being passed into the function, consider whether the size of the object is less than or equal to the size of a pointer. If so, pass by value; otherwise, pass by const reference.

如果您确实需要修改被传递给函数的对象，请考虑参数是否是可选的(即，null 是一个有效的参数).如果是，则通过指针传递；否则，通过非常量引用传递.

If you do need to modify the object being passed into the function, consider whether the parameter is optional (that is, null is a valid argument). If so, pass by pointer; otherwise, pass by non-const reference.

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