Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
609 views
in Technique[技术] by (71.8m points)

c# - Why type "int" is never equal to 'null'?

int n == 0;

if (n == null)    
{  
    Console.WriteLine("......");  
}

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)

Warning CS0472 The result of the expression is always 'false' since a value of type 'int' is never equal to 'null' of type 'int?'

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

If you want your integer variable to allow null values, declare it to be a nullable type:

int? n = 0;

Note the ? after int, which means that type can have the value null. Nullable types were introduced with v2.0 of the .NET Framework.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...