Non-Nullable becomes Nullable on return

Question

I think I've seen this question answered somewhere, but I can't find it and don't remember the answer.

Assuming Nullable-Reference-Types is enabled.

There is a method that returns a string . The caller of the method stores the resulting string into a variable. The variable will be Nullable, even if the method's return value is non-nullable.

static string MyMethod() 
{
   return "Hello World!";
}

public static void Main() 
{
   // result is of type string? here. Hence nullable.
   var result = MyMethod();

   // result2 is also nullable here.
   string result2 = MyMethod();
}

The same does not seem to happen with primitive types, but it does happen reference types, like object . Kind of defeats the purpose of NRT for me. I'm sure there's a reason for this and it's "by design".

Answer 1

This is indeed by design.

 I'm not sure why you think it is<\/em> nullable, but it definitely isn't.

Answer 2

在 C# 8.0 中，字符串被称为可以为空的“字符串！”，因此 Allow Null 注释允许将其设置为 null，即使我们返回的字符串不是 null（例如，我们进行比较检查并将其设置为如果为 null，则为默认值。）

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