c# - Alphanumeric Textbox - Validate/Sanitize clipboard text before paste

Question

On my Textbox only accepts Alphanumeric characters and a underscore using the Keypressed event but I am having problems when I right click on the textbox and pasted special characters and accepts it

Is there a way to validate the string from there before clicking paste?

Any answers will help thanks!

Answer 1

You may

1- Disable shortcuts for the textbox that would disable Ctrl-C, Ctrl-V, and the second line(will assign a empty context menu, with no items and will override the original context menu) and no context menu will appear (as it has no items):

textBox1.ShortcutsEnabled = false;
textBox1.ContextMenu = new ContextMenu();

2-If you don't want to disable paste option, you may use TextChanged event of the textbox and validate the pasted text there.