regex matching alpha character followed by 4 alphanumerics.

Question

Ok,

I need a regex for the following pattern:

-Total of 5 characters (alpha and numeric, nothing else).

-first character must be a letter (A,B,C only)

-the remaining 4 characters can be number or letter.

clarifcation: the first letter can only be A,B, or C. Example: A1234 is valid but D1234 is invalid.

Answer 1

EDIT: Grrr... edited regex due to new "clarification" :)

^[A-C][a-zA-Z0-9]{4}$

EDIT: To explain the above Regex in English...

^ and $ mean "From start to finish" (this ensures that the whole string must perfectly match)

[A-C] means "Match either A, B or C"

[a-zA-Z0-9]{4} means "Match 4 lower case letters, upper case letters or numbers"

Answer 2

Something along the lines of:

[A-C][A-Za-z0-9]{4}

I would advise taking a look at http://regexlib.com/CheatSheet.aspx if you are unfamiliar with regular expressions and try to do these kind of simple regexs yourself.

There is also plenty of online regex testing apps such as: http://regexlib.com/RETester.aspx which enable you to test your regexes without writing any code.

Answer 3

Do you mean that the first letter must be an A, B or C? Or can it be any letter?

If it has to be an A,B,or C (case sensitive), then this would be the regular expression.

[A-C][a-zA-Z0-9]{4}

Otherwise, the other answers here suffice.

Answer 4

In case this is not Perl regexps we're talking about, some cut-and-paste is needed:

[ABC][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9]

I cut-and-pasted "[a-zA-Z0-9]" four times.

Answer 5

/[ABC](?i:[a-z0-9]{4})/

Answer 6

\<[ABC]([a-zA-Z0-9]{4})\>

Answer 7

This answer is correct, but I did want to add that you can shorten it a bit with the following.

^[A-C]\w{4}$

\w means any alphaNumeric character.