CODEWITHSUNDEEP
c#asp.netvisual-studioobject
sams5817
sams5817

Reputation: 1037

Error: Object reference not set to an instance of an object

I'm develop an application using ASP.NET in c#, and I hit the following error:

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

and this is my code fragment:

Match matchNew = Regex.Match(parts[0].ToString(), @"([0]\.\d*)|[1]\.[0]$", RegexOptions.IgnoreCase);

It was testing in my local the code was perfectly fine, but it hit this error when moved the same code to my virtual environment.

I'm guessing maybe it is due to the dot net framework in my virtual environment.

Please help and thank you in advanced.

Upvotes: 2

Views: 3490

Answers (5)

Danish Khan
Danish Khan

Reputation: 1891

replace the code by this : 

if(parts != null && parts.Length>0)
{    

    if(parts[0] != null)
    {
       Match matchNew = Regex.Match(parts[0].ToString(), @"([0]\.\d*)|[1]\.[0]$", RegexOptions.IgnoreCase);
    }
}

and it would work fine. The array parts appears to be null in your case. But ideally you should also check if the array has elements and if the element in question is not null before you try to convert it to a string value.

Upvotes: 1

Sky Kelsey
Sky Kelsey

Reputation: 19280

Most likely parts[0] is null. This error is equivalent to a NullPointerException in Java.

Try setting a local variable to parts[0].ToString(); on the previous line, and see if the exception is thrown from that line instead.

I recommend only performing your match if you have something to perform it on:

if(parts[0] != null){
    Match matchNew = Regex.Match(parts[0].ToString(), @"([0]\.\d*)|[1]\.[0]$", RegexOptions.IgnoreCase);
}

Upvotes: 4

Fahad Hussain
Fahad Hussain

Reputation: 1185

It seems that your array "parts" has no elements and therefore parts[0] is null and the exception occurs due to .ToString() because null can not be converted to string.

Upvotes: 0

Shannon Cornish
Shannon Cornish

Reputation: 961

From the exception you're getting, it looks like either parts or parts[0] is null.

Perhaps consider introducing a variable for parts to see if that is null, and if so, handle either with a default value or display an error to the user, or throw an exception if that is appropriate in your situation.

object part = parts[0];
if (part == null)
{
    // part is null, either handle with default value or error.
}

Match matchNew = ...;

Upvotes: 3

Bernesto
Bernesto

Reputation: 1436

Most likely it is your array "parts" if its length is 0 then it will fail. Make sure to test it's length first.

Upvotes: 2

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