不能改变结构的成员里面泛型集合的值 [英] Can't change struct's members value inside generic collections
问题描述
想象一下结构
:
struct Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
}
和以下code:
var list = new List<Person>();
list.Add(new Person { FirstName = "F1", LastName = "L1" });
list.Add(new Person { FirstName = "F2", LastName = "L2" });
list.Add(new Person { FirstName = "F3", LastName = "L3" });
// Can't modify the expression because it's not a variable
list[1].FirstName = "F22";
当我想换属性
的值,它给了我下面的错误:
When I want to change Property
's value it gives me the following error:
Can't modify the expression because it's not a variable
虽然,当我试图数组内改变,如人[]
它时,使用的工作没有任何error.Is那里与我的code任何问题与泛型集合?
While, when I tried to change it inside an array such as Person[]
it worked without any error.Is there any problem with my code when using with generic collections?
推荐答案
当您返回结构
通过列表[]
索引,它返回条目的复制的。因此,如果您分配了名字
在那里,它只是被扔掉。因此,编译器错误。
When you return the struct
via the List[]
indexer, it returns a copy of the entry. So if you assigned the FirstName
there, it would just be thrown away. Hence the compiler error.
要么重写你的人
来引用类型类
,或做一个完整的重新分配:
Either rewrite your Person
to be a reference type class
, or do a full reassignment:
Person person = list[1];
person.FirstName = "F22";
list[1] = person;
一般来说,可变结构带来的问题,如这些,可引起头痛的道路。除非你有一个很好的理由来使用它们,你应该认真考虑改变你的人
键入
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