Hey.
I’m creating some sort of a numeration system and I don’t want the user to type certain numbers,
say for example I don’t want the user to type the number 8 inside the input field, how do I do this through code or inside the editor?
In your script you can only process the valid digits, based on what is valid at the time. Throw invalid ones away.
Either you handle the not allowed digits inside a separate if-statement and you show an error message in the UI or you only handle only the once that are allowed. For better user experience I recommend to do the first. How to retrieve the pressed key on the keyboard you find in the docs: Unity - Scripting API: Input.GetKeyDown
You should look into using regular expressions
It is much easier to control if the number of chars you want to disallow increases