How to add a piece of text to a RichTextBox from a variable?

Question

C++ / C#

Hello. The task is as follows: there is a string variable that contains text (Txt), let's say for Txt.Length = 11000 characters, I need to unload excerpts at h = 1500 characters in the RichTextBox by pressing a button (that is, the first iteration 0 ... 1500 , pressed the button 1500 ... 3000, pressed the button 3000 ... 4500, etc.) and, accordingly, back, by pressing another button. I wrote an algorithm using the for loop, I have to upload each character in turn to the RichTextBox, in terms of performance, this is very slow. Can anyone suggest a method that can immediately take a passage from a variable (with an indication of the start and end position) or suggest another solution?

Answer 1

String.Substring()

Answer 2

Try using TextRange