Represents the error that occurs when there is an attempt to dereference a null object reference. [Edit]

See Also: NullReferenceException Members

System.Object
     System.Exception
          System.SystemException
               System.NullReferenceException

[System.Runtime.InteropServices.ComVisible(true)] public class NullReferenceException : SystemException

Thread Safety

All public static members of this type are safe for multithreaded operations. No instance members are guaranteed to be thread safe.

Remarks

Note:

Applications throw the ArgumentNullException rather than NullReferenceException .

The following CIL instructions throw NullReferenceException :

• callvirt
• cpblk
• cpobj
• ldelema
• ldelem.<type>
• ldfld
• ldflda
• ldind.<type>
• ldlen
• stelem.<type>
• stind.<type>
• stfld
• throw
• unbox
• initblk

[Edit]

Example

The following example demonstrates an error that causes a NullReferenceException exception.

C# Example

using System; public class Ints { public int[] myInts; } public class NullRefExample { public static void Main() { Ints ints = new Ints(); try { int i = ints.myInts[0]; } catch( NullReferenceException e ) { Console.WriteLine( "Caught error: {0}.", e); } } }

The output is

Example

Caught error: System.NullReferenceException: Object reference not set to an instance of an object. at NullRefExample.Main().

Requirements

Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0