Mega Code Archive
0016 null reference value
<![CDATA[
A reference type variable can be assigned to null.
null means the reference type variable points to nothing.
using System;
class Rectangle
{
public int Width = 5;
public int Height = 5;
}
class Program
{
static void Main(string[] args)
{
Rectangle r1 = null;
Console.WriteLine(r1);
}
}
A value type variable cannot be assigned to null.
using System;
class Program
{
static void Main(string[] args)
{
int i = null;
Console.WriteLine(i);
}
}
Compiling the code above generates the following error message:
C:\g>csc Program.cs
Microsoft (R) Visual C# 2010 Compiler version 4.0.30319.1
Copyright (C) Microsoft Corporation. All rights reserved.
Program.cs(7,17): error CS0037: Cannot convert null to 'int' because it is a non-nullable value type
]]>