there is a text box on GUI in my application created using Unity3D. in the textbox user can input only the keys of "A-Z", "0-9" , "enter key" , "." and "," other key press should be ignored (not should print in textbox when typing). how to do this in Unity3D C#
I'm assuming you're using GUI.TextField?
It doesn't appear that there's a built-in way to restrict the text field's legal input set, however, you can achieve the validation behavior you want by writing a script:
A simple implementation of the replacement might be along the lines of