Help creating function

cx323 · 06-10-2006, 07:34 PM

This is probably a stupid error since i'm new to c# but i can't figure it out.

Code:

public static int GrabAllBetween(string strSource, string strStart, string strEnd, ref string[] strArray)
        {
            int iPos;
            int iEnd;
            int iCount = 0;
            string[] Matches = new string[100];

            iPos = strSource.IndexOf(strStart, 1);
            while (iPos > 0)
            {
                iEnd = strSource.IndexOf(strEnd, iPos);
                if (iEnd > 0)
                {
                    Matches[iCount] = strSource.Substring((iPos + strStart.Length), iEnd - iPos - (strEnd.Length - 1));
                    iPos = strSource.IndexOf(strStart, iEnd);
                }
                else
                {
                    Matches[iCount] = strSource.Substring(iPos);
                    iPos = 0;
                }
                iCount++;
                if (iCount > Matches.Length)
                {
                    string[] tmp = new string[iCount + 100];
                    Matches.CopyTo(tmp, 0);
                    Matches = tmp;
                }
            }
            if (iCount > 0)
            {
                string[] tmp = new string[iCount - 1];
                System.Array.Copy(Matches,iCount - 1,tmp,0,iCount-1); 
                strArray = tmp;
            }
            return iCount;
        }

Thats a function i created to grab all instances of a string between two other strings and put the results in an array. This is how i call it to test:

Code:

 private void button2_Click(object sender, EventArgs e)
        {
   string[] testing = new string[0];
            string test = "thisisisSa<b>thehe</b> test<b>numba</b><b>ththhhhe</b>";
            label1.Text = GrabAllBetween(test, "<b>", "</b>", ref testing).ToString();
            label2.Text = testing[0];
        }

Label1 shows 3, but label2 stays blank. I think the problem is with redimming the array in the function. I looked up how to redim preserve in c# on google, but i'm not sure if i completely understand it. Thanks for any help

Edit- now i have it displaying the third item in label2 when it should be displaying the first.

Edit - fixed it

Code:

 string[] tmp = new string[iCount + 1];
                System.Array.Copy(Matches, tmp, iCount + 1);
                strArray = tmp;

pianorain · 06-10-2006, 09:31 PM

Why are you bothering with the ref parameter and the hackish redim'ing of an array? Use some real .Net data structures; that's why they're there. Don't be afraid to return an array.

Code:

public static string[] GrabAllBetween(string strSource, string strStart, string strEnd)
{
    List<string> Matches = new List<string>();

    for (int pos = strSource.IndexOf(strStart, 0),
        end = pos >= 0 ? strSource.IndexOf(strEnd, pos) : -1;
        pos >= 0 && end >= 0;
        pos = strSource.IndexOf(strStart, end),
        end = pos >= 0 ? strSource.IndexOf(strEnd, pos) : -1)
    {
        Matches.Add(strSource.Substring(pos + strStart.Length, end - pos - strEnd.Length + 1));
    }

    return Matches.ToArray();
}

Note that your current version will fail for the following test string:

Code:

string test = "thisisisSa<b>thehe</b> test<b>numba</b><b>ththhhhe";

Your function will find three strings when only two strings are really enclosed by the bold tag.

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