System.NullReferenceException

Namespace: System

Indicates that an attempt to dereference a null object reference has occurred.

Syntax

public sealed class NullReferenceException : SystemException

Inheritance

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

Remarks

A NullReferenceException is thrown when you try to use an object variable that is currently null. This often happens when you call a method or access a member of an object without initializing the object variable first.

For example, the following code will throw a NullReferenceException because the myString variable is null:

string myString = null;
int length = myString.Length; // This line throws NullReferenceException

To avoid this exception, you should always check if an object variable is null before attempting to use it, or ensure that it is properly initialized.

Constructors

Name	Description
NullReferenceException()	Initializes a new instance of the `NullReferenceException` class.
NullReferenceException(string message)	Initializes a new instance of the `NullReferenceException` class with a specified error message.
NullReferenceException(string message, Exception innerException)	Initializes a new instance of the `NullReferenceException` class with a specified error message and a reference to the inner exception that is the cause of the current exception.

Fields

No public fields are exposed by this class.

Properties

Name	Description
`HResult`	Gets or sets the HRESULT value assigned to the specified exception.
`InnerException`	Gets a reference to the inner exception that is the cause of the current exception.
`Message`	Gets an error message that describes the current exception.
`Source`	Gets or sets the name of the application or the object that causes the error.
`StackTrace`	Gets a string representation of the immediate frames of the call stack.
`TargetSite`	Gets the method that throws the current exception.

Methods

Name	Description
`ToString()`	Overrides `System.Exception.ToString()` to include the name of the exception and the decimal representation of the HRESULT.