Length cannot be less than zero. Parameter name: length

Question

1.00/5 (1 vote)

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C#

protected void asd_Click(object sender, EventArgs e)
        {
            if (Common.Common.ApplicationInformation.LoggedInUser.RGroupIds != null)
            {
                string Documentid = string.Empty;
                string GroupIds = string.Empty;
                string DocumentIds = string.Empty;
                string ContactIds = string.Empty;
                //----------------
                if (Session["ReportDocumentIDs"].ToString() != null)
                {
                    DocumentIds = Session["ReportDocumentIDs"].ToString();
                    Documentid = DocumentIds.Substring(0, DocumentIds.LastIndexOf(','));
                }
                else
                {
                    Documentid = null;
                }

Posted 8-Jun-15 19:56pm

Sambit_Sahoo

Updated 8-Jun-15 20:23pm

v2

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Comments

Sinisa Hajnal 9-Jun-15 2:14am

Which line? Only thing I see that could cause the error is the fact that you are not checking if Session["ReportDocumentIDs"] is null before using it (calling ToString() is usage before checking)...

Sambit_Sahoo 9-Jun-15 2:15am

Documentid = DocumentIds.Substring(0, DocumentIds.LastIndexOf(','));

2 solutions

Solution 1

Please read the documentation[^]. It happens because

MSDN wrote:
String.LastIndexOf method reports the zero-based index position of the last occurrence of a specified Unicode character or string within this instance. The method returns -1 if the character or string is not found in this instance.

So, you can not return substring which starts with zero and ends with -1 ;)

Posted 8-Jun-15 20:36pm

Maciej Los

Updated 8-Jun-15 20:38pm

v2

Comments

Sascha Lefèvre 9-Jun-15 2:38am

5ed.

Maciej Los 9-Jun-15 2:40am

Thank you, Sascha.

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sasanka sekhar panda · Accepted Answer · 2015-06-08T20:42:00

Length cannot be less than zero.

Documentid = DocumentIds.Substring(0, DocumentIds.LastIndexOf(','));

This exception will occur if you are passing a DocumentIds without a ',' ;

DocumentIds.LastIndexOf(',') this will return -1;

then Documentid = DocumentIds.Substring(0, -1); throws exception..

Try to handle it..If you need more help let me know..