C++ 通过引用传递向量
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/7966233/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Passing vectors by reference
提问by SirYakalot
If I have a vector of objects in one class which I want to change in another, I would try and pass all the information by reference.
如果我想在另一个类中更改对象向量，我会尝试通过引用传递所有信息。
What exactly do I need to pass by reference though? The vector? The objects? Both?
我究竟需要通过引用传递什么？向量？对象？两个都？
Essentially what I'm asking is: What is the difference between these?
基本上我要问的是：这些之间有什么区别？
vector&<object> blah; // A reference to a vector of objects?
vector<object&> blah; // A vector of references to objects?
vector&<object&> blah; // A reference to a vector of references to objects???
I'm not actually sure how referencing of array like containers work. Are these legal?
我实际上不确定像容器这样的数组的引用是如何工作的。这些合法吗？
回答by Cat Plus Plus
vector&<object>is a syntax error. vector<object&>is invalid, because a vector's value type must be assignable. vector&<object&> blahis a syntax error.
vector&<object>是语法错误。vector<object&>无效，因为向量的值类型必须是可分配的。vector&<object&> blah是语法错误。
A reference to a vector is vector<T>&.
对向量的引用是vector<T>&。
回答by Kerrek SB
You cannot have a vector of references. Vector elements must be copyable and assignable, which references are not. So only the first option is actually an option, but it's spelled std::vector<Object> &.
你不能有一个引用向量。向量元素必须是可复制和可分配的，而引用则不是。所以只有第一个选项实际上是一个选项，但它的拼写是std::vector<Object> &。
Note that v[1]already returns a referenceto the second element, so you can happily pass individual elements by reference.
请注意，v[1]已经返回了对第二个元素的引用，因此您可以愉快地通过引用传递单个元素。
It is possible to have a vector of reference-wrappers a la std::ref, but if you don't know what that is, you probably shouldn't be using it at this point.
可以有一个引用包装向量 a la std::ref，但如果您不知道那是什么，那么此时您可能不应该使用它。
回答by jk.
Another option is to pass around iterators instead of containers. This is the approach the standard library takes in <algorithm>. They are slightly more verbose at the calling site, but they have the advantage that they work for parts of a collection as well as complete collections and decouples the algorithm from the container.
另一种选择是传递迭代器而不是容器。这是标准库采用的方法<algorithm>。它们在调用站点上稍微冗长一些，但它们的优点是它们适用于集合的一部分以及完整的集合，并将算法与容器分离。
Lastly, of course, it's worth while checking you know your algorithms as there may already be one that does what you want.
最后，当然，检查您是否了解您的算法是值得的，因为可能已经有一个可以做您想要的。
