Regexp Result
preg_match("/[A-Z]{3}/", "FuZ") False; the regexp will match precisely three uppercase letters
preg_match("/[A-Z]{3}/i", "FuZ") True; same as above, but case-insensitive this time
preg_match("/[0-9]{3}-[0-9]{4}/", "555-1234") True; precisely three numbers, a dash, then precisely four. This will match local U.S. telephone numbers, for example
preg_match("/[a-z]+[0-9]?[a-z]{1}/", "aaa1") True; must end with one lowercase letter
preg_match("/[A-Z]{1,}99/", "99") False; must start with at least one uppercase letter
preg_match("/[A-Z]{1,5}99/", "FINGERS99") True; "S99", "RS99", "ERS99", "GERS99", and "NGERS99" all fit the criteria
preg_match("/[A-Z]{1,5}[0-9]{2}/i", "adams42") True