C# TextBox Casting: Using 'as' Keyword for Safe Conversion

This line of code is used in C# to cast the sender object to a TextBox class. It is commonly used in event handlers where the sender object is the control that raised the event. By casting it to a TextBox class, you can access the properties and methods specific to that class.

The 'as' keyword is used for safe type casting. If the sender object is not a TextBox or a subclass of TextBox, the result will be null instead of throwing an exception.