int? parameter

Rod P

Hi,
I am inheriting some C#/Asp code from a programmer that believes in not comments at all. There are a few functions that have a parameter that is int? and I can't seem to find a reference to this anywhere as to what exactly this means. For example:

public AcitonResult Create(int? data_type_id, int? department_id, string[] CountyList){ ...}mentBasisList,

Can anyone tell me what exaclty placing the ? on the int type does?

Thanks,
Rod

4 Replies

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Chris Riley16y ago
Accepted answer
I think it means its a nullable type

See http://msdn.microsoft.com/en-us/library/2cf62fcy.aspx
sham suman16y ago
Hi,

Here int? is means nullable type.
Nullable types are declared in one of two ways:

1. System.Nullable variable

-or-

2. T? variable

T is the underlying type of the nullable type.

The reason is int is a value type and null can't be assign into value type because it through exception.
kailash biswal16y ago
Generally we can not assign a null value to a value type, if u asign a null value it's throgh a execption , tto assign a null value to value type we are define ? operator
Rod P16y ago
Thanks. That looks to be it.