Question

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, or C only)

• the remaining 4 characters can be number or letter.

Clarifcation: the first letter can only be A, B, or C.

Examples:

• A1234 is valid
• 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’