Regex for matching a music Chord
music-notation, regex
Solution
Change `[` and `]` to `(` and `)` in the following lines:
String accidentals = "(#|##|b|bb)";
String chords = "(maj7|maj|min7|min|sus2)";
Otherwise you're just making character classes, so `[maj7|maj|min7|min|sus2]` simply matches on the letter `m`.
I'm guessing you also want to add an ending anchor `$`? I see you had problems with that before, but that's probably because of the aforementioned issue.
Also, might you want `(#|##|b|bb)` to be optional (i.e., with `?`: `(#|##|b|bb)?`)?
Problem
I am trying to write a function to parse the string representation of a musical chord. Example: C major chord -> Cmaj (this is what I want to parse) Just to make it clear, a chord is made of three different parts: - the note (C, D, E, F, G, A) - the accidentals for that note (#, ##, b, bb) - the chord name For those, music savvy, I am not considering slash chords (on purpose). The below function is almost working. However it still doesn't work for the following case: - "C#maj" # matches and should - "C#maj7" # matches and should - "C#maj2" # mathches and shouldn't I suppose that if I could make the `chords` regex part forced to be at the end of the regex, did the trick. I have tried using the `$` both before and after this String but it didn't work. Any idea? Thanks. ``` public static void regex(String chord) { String notes = "^[CDEFGAB]"; String accidentals = "[#|##|b|bb]"; String chords = "[maj7|maj|min7|min|sus2]"; String regex = notes + accidentals + chords; Pattern pattern = Pattern.compile(regex); Matcher matcher = pattern.matcher(chord); System.out.println("regex is " + regex); if (matcher.find()) { int i = matcher.start(); int j = matcher.end(); System.out.println("i:" + i + " j:" + j); } else { System.out.println("no match!"); } } ```