CODEWITHSUNDEEP
c#regexrichtextbox
user2976089
user2976089

Reputation: 355

RichTextBox Regex Error

I am trying to use Regex to highlight numbers in my RichTextBox RTB, and it works fine, except when I press move the caret position to above where I was, it selects the stuff below, and when I type, it dissapears, unless I am constantly pressing the left key, which is a real nuisance.

Code:

MyRegex.cs

namespace REGEX_MY
{
    public class REGEX_CLASS
    {
        public static RichTextBox HIGHLIGHT(RichTextBox RTB, int StartPos)
        {
            Regex Red = new Regex("1|2|3|4|5|6|7|8|9|0");
            RTB.SelectAll();
            RTB.SelectionColor = Color.White;
            RTB.Select(RTB.Text.Length, 1);

            foreach (Match Match in Red.Matches(RTB.Text))
            {
                RTB.Select(Match.Index, Match.Length);
                RTB.SelectionColor = Color.Blue;
                RTB.SelectionStart = StartPos;
                RTB.SelectionColor = Color.White;
            }
            return RTB;
        }
    }          
}

MyForm.cs

public void DoIt()
{
    RTB = REGEX_MY.REGEX_CLASS.HIGHLIGHT(RTB, RTB.SelectionStart);
}

Thanks :)

Upvotes: 1

Views: 333

Answers (1)

desko27
desko27

Reputation: 1736

RTB.Select(Match.Index, Match.Length) in foreach statement is jumping a 1 length selection over the matched digits. When it finishes, it keeps the selection over the last matched digit, and when you press any key the selection does not disappear but the cursor moves forward, so the next character gets overwritten.

The solution is to bring back the cursor to the starting position without selection range just after the foreach statement gets finished, like this RTB.Select(StartPos, 0)

foreach (Match Match in Red.Matches(RTB.Text))
{
    RTB.Select(Match.Index, Match.Length);
    RTB.SelectionColor = Color.Blue;
    RTB.SelectionStart = StartPos;
    RTB.SelectionColor = Color.White;
 }
 RTB.Select(StartPos, 0);
 return RTB;

Upvotes: 2

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