var regex = new Regex(textBox1.Text);
List<string> matchingLines = new List<string>();
foreach (var listBoxItem in targetListBox.Items)
{
var texts = listBoxItem.Text.Split('.');
foreach (var t in texts)
{
if (regex.IsMatch(t))
{
matchingLines.Add(listBoxItem.Text);
break;
}
}
}
targetTextBox2.Lines =matchingLines.ToArray();