问题描述
int n == 0;
if (n == null)
{
Console.WriteLine("......");
}
表达式 (n == null) 的结果是否总是 false 因为
int 类型的值永远不等于 null 类型 int?(见下面的警告)
Is it true that the result of expression (n == null) is always false since
a value of type int is never equal to null of type int? (see warning below)
警告 CS0472 表达式的结果始终为false"，因为int"类型的值永远不会等于int"类型的null"?
Warning CS0472 The result of the expression is always 'false' since a value of type 'int' is never equal to 'null' of type 'int?'
推荐答案
如果您希望整数变量允许空值，请将其声明为 可空类型:
If you want your integer variable to allow null values, declare it to be a nullable type:
int? n = 0;
注意 int 之后的 ?，这意味着该类型可以具有值 null..NET Framework v2.0 引入了可空类型.
Note the ? after int, which means that type can have the value null. Nullable types were introduced with v2.0 of the .NET Framework.
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