Help constructing regex

Question

I need to know if a string matches a number of different criterias. I'm trying to solve this by using a regular expression and then see if it matches (in Java: str.matches(myRegex);), but I can't get it right.

The criterias are as follows:

• The string to match is constructed of 4 letters, [A-Z]
• It may be preceeded (but not necessarily) by one of "-", "+" or "VC"
• It shall only match strings containing exactly 4 letters (and the possibly preceeding characters)

Examples:

• "SHSN" -> match
• "+SHRA" -> match
• "VCSHRA" -> match
• "CAVOK" -> no match
• "-+SHSN" -> no match

Is this possible to do in one single regex? Or should it be done in code or a combination of the two?

Thanks,

Linus

Answer 1

Try this regular expression:

^([+-]|VC)?[A-Z]{4}$