Making a textbox display its characters in a particular case (upper, lower, or title) is very easy with the help of the CharacterCasing
property, which uses the values of the enum Forms.CharacterCasing
In the following example, CharacterCasing is used to display all typed characters in uppercase:
textBox1.CharacterCasing = System.Windows.Forms.CharacterCasing.Upper;
You can also set this at design time.