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[book] [en] Pro C# 2008 and the NET 3.5 Platform Fourth Edition

// Get int from "database".

int? i = dr.GetIntFromDatabase();

if (i.HasValue)

Console.WriteLine("Value of 'i' is: {0}", i.Value);

else

Console.WriteLine("Value of 'i' is undefined.");



// Get bool from "database".

bool? b = dr.GetBoolFromDatabase();

if (b != null)

Console.WriteLine("Value of 'b' is: {0}", b.Value);

else

Console.WriteLine("Value of 'b' is undefined.");



Console.ReadLine();

}

The ?? Operator

The final aspect of nullable types to be aware of is that they can make use of the C# ?? operator.

This operator allows you to assign a value to a nullable type if the retrieved value is in fact null. For

this example, assume you wish to assign a local nullable integer to 100 if the value returned from

GetIntFromDatabase() is null (of course, this method is programmed to always return null, but I

am sure you get the general idea):

static void Main(string[] args)

{

Console.WriteLine("***** Fun with Nullable Data *****\n");



DatabaseReader dr = new DatabaseReader();

...



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