How to insert a letter into an integer function?

Question

Delphi

Hey! The question arose about how to enter a variable string into integer, namely a letter.
For example, there is a ComboBox on the form that contains all the letters of the alphabet from A to Z.
There is a function to get the disk number by its letter: GetPhysicalDiskNumber('C')
So, how to take the value from the ComboBox instead of C in this function?

Answer 1

GetPhysicalDiskNumber(ComboBox.Text)