更新时间:2023-11-29 08:25:22
在C#7.3之前,您有两种选择:使用.等于
,或者可以写出 ==
比较,对于本身支持 ==
:
Prior to C# 7.3, you had two choices: use .Equals
, or you can write out the ==
comparison long-hand, for elements that themselves support ==
:
(a, b).Equals((c, d)) // true if a.Equals(c) && b.Equals(d)
a == c && b == d // works if the types support ==
(有关以下内容的详细信息 Equals()
的工作原理,请查看源代码.)
(For details of how Equals()
works, check out the source.)
从C#7.3开始,对 ==
的直接支持已添加到值元组:
As of C# 7.3, direct support for ==
has been added to value tuples:
(a, b) == (c, d) // compiler converts to a == c && b == d
请注意,这里的 ==
不是元组类型定义的运算符.这是一个编译技巧",它(对于嵌套元组)递归地对每个元素执行 ==
.结果,仅当元素本身支持 ==
时,才可以使用此技术.结果,这种方法不适用于泛型,除非限于确实支持 ==
的类型.因此,以下代码将无法编译:
Note that ==
here is not an operator defined by the tuple types. It's a "compiler trick" that recursively (for nested tuples) performs ==
on each of the elements. As a result, this technique can only be used if the elements support ==
themselves. As a result, this approach does not work for generics, unless constrained to types that do support ==
. So the following code will not compile:
public bool Compare<T1, T2>((T1 a, T2 b) x, (T1 a, T2 b) y) => x == y