CODEWITHSUNDEEP
c#asp.netregex
WeakTaenie
WeakTaenie

Reputation: 247

Error When Using Regex Expression

This Code is used to generate New ID based on my last ID. Previously When I generate ID for D0001, D0002 ("^\D+"), etc.... has no Problem But now for C0001,C0002 There is an error Regarding my expression ("^\C+").... Sorry for my English . 

string autoquery = "select top(1) CommentID from [Comment] order by CommentID DESC";
        SqlCommand cmd1 = new SqlCommand(autoquery, cn);
        cn.Open();
        SqlDataReader dr = cmd1.ExecuteReader();
        dr.Read();
        string autoID = dr["CommentID"].ToString();
        var prefix = Regex.Match(autoID, "^\\C+").Value;
        var number = Regex.Replace(autoID, "^\\C+", "");
        var i = int.Parse(number) + 1;
        var newString = prefix + i.ToString(new string('0', number.Length));

        cn.Close();

Upvotes: 0

Views: 50

Answers (2)

JKennedy
JKennedy

Reputation: 18799

Which line does the error occur on?

my guess would be that the error occurs on the line

    var prefix = Regex.Match(autoID, "^\\C+").Value;
    var number = Regex.Replace(autoID, "^\\C+", "");

because your Regex has found no matches. I would change this to

    var prefix = Regex.Match(autoID, "^[A-Za-z]+").Value;
    var number = Regex.Replace(autoID, "^[A-Za-z]+", "");

to match all letters a-z in any case rather than just the letter C or D

another way if to defensively code against your regex not finding any matches

    var prefix = Regex.Match(autoID, "^\\C+")
    if (prefix.Success)
    {
         var number = Regex.Replace(autoID, "^\\C+", "");
         var i = int.Parse(number) + 1;
         var newString = prefix + i.ToString(new string('0', number.Length));
    }

Upvotes: 1

vks
vks

Reputation: 67968

^C\\d+

You should try this.When you want to match C you need not escape it. \\C can become some special directive like \\d or \\D.

Upvotes: 2

Related Questions