问题描述
我可以用 null 或一些空值初始化 var 吗?
Can I initialize var with null or some empty value?
推荐答案
C# 是一种严格/强类型语言.var 是为 匿名类型 的编译时类型绑定引入的，但你可以将 var 用于设计时已知的原始和自定义类型.在运行时，没有什么像 var，它被一个实际的类型所取代，它要么是引用类型，要么是值类型.
C# is a strictly/strongly typed language. var was introduced for compile-time type-binding for anonymous types yet you can use var for primitive and custom types that are already known at design time. At runtime there's nothing like var, it is replaced by an actual type that is either a reference type or value type.
当你说，
var x = null;
编译器无法解决这个问题，因为没有类型绑定到 null.你可以这样弄.
the compiler cannot resolve this because there's no type bound to null. You can make it like this.
string y = null;
var x = y;
这会起作用，因为现在 x 可以在编译时知道它的类型，在这种情况下是字符串.
This will work because now x can know its type at compile time that is string in this case.
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