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RichTextBox format line by button click vb.net 2010

Hi Experts,

I'm trying writing to write a winform app with a RTB and button. The button follows the cursor/caret up or down depending on carriage return (which works great thanks to the mighty kaufmed from previous question... Previous Question

The purpose of the button is to format whatever text is on same line as button.
for example: if i want all the text on line 5 to change color to GREEN, then pressing this button will do so. and not continue on another line.

I found the code beow (from a google search) and inserted into my button click, which works great if I don't add Label1.Text in line 2 / 4... works with array (actual number).

1    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
2    RichTextBox1.SelectionStart = RichTextBox1.Text.IndexOf(RichTextBox1.Lines(Label1.Text))  'Sets the selection 3    length as the length of the line 3. At this point, we have now set the start and end positions of the selection.
4    RichTextBox1.SelectionLength = RichTextBox1.Lines(Label1.Text).Length
5    RichTextBox1.SelectionColor = Color.Green   'Sets the color of the selected text to Green.
6
7    End Sub

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The ERROR I'm getting is
Message=Index was outside the bounds of the array.

because Label1 shows line numbers... I thought it would be easy to pass it through a label.
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Fernando SotoRetired
Distinguished Expert 2017

Commented:
Hi Roberto;

You should have gotten an error pointing to this part of the following line of code, RichTextBox1.Lines(Label1.Text), because the lines property is an array of String's and you are indexing that array with a string value from Label1.Text. You need an Integer value to do that indexing.

RichTextBox1.SelectionStart = RichTextBox1.Text.IndexOf(RichTextBox1.Lines(Label1.Text))

Author

Commented:
Hi Fernando,

I understand that you're saying... it's just connecting the dots now. I 'm trying to draw from lineCount, but it's encased in RichTextBox1_TextChanged....

RichTextBox1.SelectionStart = RichTextBox1.Text.IndexOf(RichTextBox1.Lines(lineCount)) ' would be better, but it doesn't work.
Fernando SotoRetired
Distinguished Expert 2017

Commented:
Try it like this Roberto and see if it gives you what you are looking for.

RichTextBox1.SelectionStart = RichTextBox1.Text.IndexOf(RichTextBox1.Lines.Count) 

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Author

Commented:
Thanks Fernando,

I get the following...
Message=
InvalidArgument=Value of '-1' is not valid for 'SelectionStart'.
Retired
Distinguished Expert 2017
Commented:
With is part of the statement, RichTextBox1.SelectionStart, you should be trying to set the start of the Selected text in the RichTextBox. Looking at the right side of the equals sign of the statement, RichTextBox1.Text.IndexOf(RichTextBox1.Lines.Count), would suggest that you are trying to set the start character position from the beginning to the value of the number of lines in the text box which I do not think you what.

What do you wish to do?

Author

Commented:
ah yes, I think you've "Hit the nail on the head"... You're right... I guess what i want is to set the format anywhere along the line (instead of at the font).
I've been trying to get the BUTTON to highlight the line before actioning it.
Since your last comment, I've been experimenting with ysendkeys(end)

RichTextBox1.Focus()
        RichTextBox1.Focus()
        SendKeys.Send("{HOME}+{END}")
        RichTextBox1.SelectionAlignment = HorizontalAlignment.Center
        RichTextBox1.AppendText(Environment.NewLine)
        RichTextBox1.ScrollToCaret()
        RichTextBox1.SelectionAlignment = HorizontalAlignment.Left

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This seems to work for me ;)

Author

Commented:
Thanks Fernando! Super Job ;)
Fernando SotoRetired
Distinguished Expert 2017

Commented:
Not a problem Roberto, glad I was able to help.