C#

N a v a n e e t h wrote:

I succeeded in creating collectionclass

public class YourItemsCollection : CollectionBase, IDisposable
{
 //...
}

public class YourItemsCollectionConverter: ExpandableObjectConverter
{
 //...
}

public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)

public override PropertyDescriptorCollection GetProperties(ITypeDescriptorContext context, object value, Attribute[] filter)

[TypeConverter(typeof(YourItemsCollectionConverter))]

string[] lines=richTextBox1.Lines;
int linesLength=lines.Lenght;
for (int a = c; a < linesLength; a++) {
    selectionlength += lines[a].Length + 1;
    ...
}

Luc Pattyn wrote:

1.
take richTextBox1.Lines out of the for line and the for block,

Luc Pattyn wrote:

I can't tell whether you use colors, bold, etc.
If not, consider a ListBox, it is faster at anything it does (and it only
selects entire lines).

Luc Pattyn wrote:

2.
If not, consider a ListBox, it is faster at anything it does (and it only
selects entire lines).

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace rtfTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            richTextBox1.Text = "[ID] = 0000\nlines\n[END]\n[ID] = 1234\nlines for 1234\n[END]";
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string beginTag = "[ID] = 1234";
            string endTag = "[END]";
            int startPosition = richTextBox1.Find(beginTag);
            if (startPosition >= 0)
            {
                startPosition = startPosition + beginTag.Length+1;// we start at the first line after beginTag
                int endPosition = richTextBox1.Find(endTag,startPosition,RichTextBoxFinds.MatchCase);
                if (endPosition > startPosition)
                    richTextBox2.Text = richTextBox1.Text.Substring(startPosition , endPosition - startPosition );
            }
                
        }
    }
}