Delete specific row in .NET RichTextBox

Question

How to delete a specific line of text in a RichTextBox?

Answer 1

Another solution:

private void DeleteLine(int a_line)
{
    int start_index = richTextBox.GetFirstCharIndexFromLine(a_line);
    int count = richTextBox.Lines[a_line].Length;

    // Eat new line chars
    if (a_line < richTextBox.Lines.Length - 1)
    {
        count += richTextBox.GetFirstCharIndexFromLine(a_line + 1) -
            ((start_index + count - 1) + 1);
    }

    richTextBox.Text = richTextBox.Text.Remove(start_index, count);
}

Answer 2

Try the following:

Dim lst As New ListBox  
        Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click  
            Me.Controls.Add(lst)  
            For Each cosa As String In Me.RichTextBox1.Lines  
                lst.Items.Add(cosa)  
            Next  
            lst.Items.RemoveAt(2) 'the integer value must be the line that you want to remove -1  
            Me.RichTextBox1.Text = String.Empty  
            For i As Integer = 0 To lst.Items.Count - 1  
                If Me.RichTextBox1.Text = String.Empty Then  
                    Me.RichTextBox1.Text = lst.Items.Item(i)  
                Else  
                    MeMe.RichTextBox1.Text = Me.RichTextBox1.Text & Environment.NewLine & lst.Items.Item(i).ToString  
                End If  
            Next  
        End Sub

http://social.msdn.microsoft.com/Forums/en-US/vbgeneral/thread/63647481-743d-4e55-9043-e0db5106a03a/

Answer 3

tomanu,

int start_index = LogBox.GetFirstCharIndexFromLine(linescount);
int count = LogBox.GetFirstCharIndexFromLine(linescount + 1) - start_index;
LogBox.Text = LogBox.Text.Remove(start_index, count);

, - 2.

Answer 4

( , ++ ). . , "ReadOnly" , .

richTextBox.SelectionStart = richTextBox.GetFirstCharIndexFromLine(your_line);
richTextBox.SelectionLength = this.richTextBox.Lines[your_line].Length+1;
this.richTextBox.SelectedText = String.Empty;

Answer 5

, . .Split .Text ,

string[] lines = richTextBox1.Text.Split( "\n".ToCharArray() )

-, .Text .

:

        string[] lines = richTextBox1.Text.Split("\n".ToCharArray() );


        int lineToDelete = 2;           //O-based line number

        string richText = string.Empty;

        for ( int x = 0 ; x < lines.GetLength( 0 ) ; x++ )
        {
            if ( x != lineToDelete )
            {
                richText += lines[ x ];
                richText += Environment.NewLine;
            }
        }

        richTextBox1.Text = richText;

10 , StringBuilder .

Answer 6

, , .

Answer 7

.

public static void DeleteLine([NotNull] this RichTextBox pRichTextBox, int pLineIndex) {
   if (pLineIndex < 0 || pLineIndex >= pRichTextBox.Lines.Length)
      throw new InvalidOperationException("There is no such line.");

   var start = pRichTextBox.GetFirstCharIndexFromLine(pLineIndex);
   var isLastLine = pLineIndex == pRichTextBox.Lines.Length - 1;
   var nextLineIndex = pLineIndex + 1;

   var end = isLastLine
      ? pRichTextBox.Text.Length - 1
      : pRichTextBox.GetFirstCharIndexFromLine(nextLineIndex) - 1;

   var length = end - start + 1;
   pRichTextBox.Text = pRichTextBox.Text.Remove(start, length);
}

Unit tests:

(used \ninstead Environment.NewLine, since at least for me RTB automatically replaces \r\nonly \n)

[TestMethod]
public void TestDeleteLine_SingleLine() {
   var rtb = new RichTextBox();
   rtb.Text = "This is line1.\n";
   rtb.DeleteLine(0);
   var expected = "";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod]
public void TestDeleteLine_BlankLastLine() {
   var rtb = new RichTextBox();
   rtb.Text = "\n";
   rtb.DeleteLine(1);
   var expected = "\n";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod]
public void TestDeleteLine_SingleLineNoEOL() {
   var rtb = new RichTextBox();
   rtb.Text = "This is line1.";
   rtb.DeleteLine(0);
   var expected = "";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod]
public void TestDeleteLine_FirstLine() {
   var rtb = new RichTextBox();
   rtb.Text = "This is line1.\nThis is line2.\nThis is line3.";
   rtb.DeleteLine(0);
   var expected = "This is line2.\nThis is line3.";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod]
public void TestDeleteLine_MiddleLine() {
   var rtb = new RichTextBox();
   rtb.Text = "This is line1.\nThis is line2.\nThis is line3.";
   rtb.DeleteLine(1);
   var expected = "This is line1.\nThis is line3.";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod]
public void TestDeleteLine_LastLine() {
   var rtb = new RichTextBox();
   rtb.Text = "This is line1.\nThis is line2.\nThis is line3.";
   rtb.DeleteLine(2);
   var expected = "This is line1.\nThis is line2.\n";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod]
public void TestDeleteLine_OneBlankLine() {
   var rtb = new RichTextBox();
   rtb.Text = "\n";
   rtb.DeleteLine(0);
   var expected = "";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod]
public void TestDeleteLine_BlankLines() {
   var rtb = new RichTextBox();
   rtb.Text = "\n\n\n\n\n";
   rtb.DeleteLine(2);
   var expected = "\n\n\n\n";
   Assert.AreEqual(expected, rtb.Text);
}

[TestMethod, ExpectedException(typeof(InvalidOperationException))]
public void TestDeleteLine_Exception_BeforeFront() {
   var rtb = new RichTextBox();
   rtb.Text = "\n\n\n\n\n";
   rtb.DeleteLine(-1);
}

[TestMethod, ExpectedException(typeof(InvalidOperationException))]
public void TestDeleteLine_Exception_AfterEnd() {
   var rtb = new RichTextBox();
   rtb.Text = "\n\n";
   rtb.DeleteLine(3);
}

Answer 8

A lot of good answers, but I find a lot very complicated.

string[] LinesArray = this.richTextBox1.Lines;

this.richTextBox1.Clear();

for (int line = 0; line < LinesArray.Length; line++)
{
if (!LinesArray[line].Contains("< Test Text To Remove >"))
{
this.richTextBox1.AppendText(LinesArray[line] + Environment.NewLine);
}
}

I hope this helps others, 0)