PHP Regular Expressions Using +, *, And ? – String Function

 
Regexp                                              Result
 
preg_match("/[A-Z]+/", "123")                       False
 
preg_match("/[A-Z][A-Z0-9]+/i", "A123")             True
 
preg_match("/[0-9]?[A-Z]+/", "10GreenBottles")      True; matches "0G"
 
preg_match("/[0-9]?[A-Z0-9]*/i", "10GreenBottles")  True
 
preg_match("/[A-Z]?[A-Z]?[A-Z]*/", "")              True; zero or one match, then zero or one match, then zero or more means that an empty string matches