Learning to Program

Validation

In this chapter, you have written a pretty good phone number validation (for U.S. phone numbers). Nearly every time I have to do validation, I use regular expressions. Emails are especially difficult to validate; do a search for “email regular expression,” and you will see what I mean. Again, just because a phone number or email address matches a regular expression does not mean that it is valid, but regular expressions can tell you whether the string at least looks reasonable.