You'll often want to verify that a string has a certain format—that an email address looks valid, or a date is formatted the way you want, or perhaps that a credit card number passes a basic validity test. There are two ways to verify string formats: using string methods, which break strings apart and analyze them, and using a technique called regular expressions to define patterns of strings as valid or invalid.
To verify string formats by breaking them apart, you need these five useful string methods:
split(). I'll cover each method and show how to use them to verify an email address or date. The credit card script is long, so I don't discuss it here, but ...