how to check for null integers in codeBehind

[raghu3]

The problem being, the integer is not a user input.
I need to say:
if (id != null) {
}

It does not compile, I get the following:
Operator '!=' cannot be applied to operands of type 'int' and '<null>'

If I try
Convert.ToInt32(id)
It compiles but I get a runtime error:
System.NullReferenceException: Object reference not set to an instance of an object.

Any work around ?

 

[ca8msm]

Does checking if it is null work? e.g.

if(id == null)

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[checkai]

Isn't there a IsDBNull or something like that?

"...your mom goes to college..."

 

[raghu3]

No it does not ... does not compile

 

[ca8msm]

You could use an object instead then and check if that object is null - if it isn't convert it to an int otherwise do what ever validation you are trying to do..


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[jshurst]

I don't think that an integer can be null. Once you declare it then it is set to "0." You could check to see if it is zero.

 

[jshurst]

I could be wrong on that. Check out this article...

http://msdn2.microsoft.com/en-us/library/1t3y8s4s(vs.80).aspx

I can't get this to work though, but I'm not very experienced in C#.

 

[BoulderBum]

Nullable types are new to .NET 2.0. You won't be able to check if an int is null in any version of .NET, and you'll have to use an int? (nullable int) in 2.0.

Otherwise you'll have to do what others suggest which is to check a database value against System.DbNull.Value or assign a default value that indicates "null" (like int.MinValue).