Compute number of lines typed in a rich text box control

Question

I would like to know more about computing the number of lines in a rich text box control.

From there, I would also like to include it in a for loop structure.

Also, what is the length property of the lines object of the rich text box control do?

Answer 1

To find out the number of lines displayed in the RichTextBox, run the GetLineFromCharIndex method.

private void Form1_Load(object sender, EventArgs e) {
    richTextBox1.Text = "Hello, World! \r\n Hello, World!Hello, World!Hello, World!Hello, World!";
}

private void RichTextBox1_TextChanged(object sender, EventArgs e) {
    RichTextBox rbox = (RichTextBox)sender;
    int len = rbox.TextLength;
    int lines;
    if (len > 0) {
        lines = rbox.GetLineFromCharIndex(len - 1) + 1;
    } else {
        lines = 0;
    }
    label1.Text = $"lines:{lines}";
}

see also:

GetCharIndexFromPosition
GetPositionFromCharIndex

There are many messages to provide layout information.

「Edit Control Messages」

https://learn.microsoft.com/en-us/windows/win32/controls/bumper-edit-control-reference-messages

EM_GETLINECOUNT, EM_LINEFROMCHAR, ...etc

Answer 2

Hi, @John

Lines is Array type string[]. And Length properties: Gets the total number of elements in all the dimensions of the Array. Length represents the number of lines (end with \r\n is one line).

Eg.
richTextBox1.Text = "Hello, World! \r\n Hello, World!Hello, World!Hello, World!Hello, World!";

Enabled word wrap, but the length is 2.

Best regards,

Minxin Yu

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