How do I ensure a text box is alphanumeric but without a leading digit?

Question

My web application contains a text box for which I would like to restrict its input. I would like to prevent the user from entering text that:

• Starts with white s

Answer 1

Not to start with white space of alpha numeric: [a-zA-Z]+
Followed by 0 or more alphanumeric: [a-zA-Z0-9]*

Final expression

^[a-zA-Z]+[a-zA-Z0-9]*$