What is a NullReferenceException, and how do I fix it in C#?

Question

Khushi Singh · Answer

NullReferenceException occurs in 
C# due to attempts to access member items from objects that remain uninitialized and thus become null. Among the many runtime exceptions in C#, the
NullReferenceException stands out as it indicates a reference variable has no assigned valid object.
The exception initiates from a wide variety of occurrences including
Running a method from a non-initiated object instanceA null reference exception occurs when your program attempts to reach a property or field from an object which lacked initialization.The program tries to retrieve data from an uninitialized collection element or array section
To avoid this exception
All objects need initialization before their members can be accessed.Insert null reference checks with (if (obj != null)) to prevent dealing with null values.The null-conditional operator (?.) provides safer access when used in the code.You should debug and trace the values of objects during runtime to verify proper initialization occurs.
Code contains a secure method to deal with this situation as follows:
string name = null;
if (name != null)
{
   int length = name.Length;
   Console.WriteLine("Length of name: " + length);
}
else
{
   Console.WriteLine("The variable 'name' is null.");
}
The program verifies that variable name contains null value prior to accessing the Length property. The check on name for null value stops the
NullReferenceException from occurring and enables the program to manage this potentially problematic condition.
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What is a NullReferenceException, and how do I fix it in C#?

Ashutosh Kumar Verma

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