Question

What I am trying to do is replace A#, A#m,… with another font-color version like this:

preg_replace('/\bA#m\b/','<span style="color:#910202;">A#m</span></a>',$content);
preg_replace('/\bA#\b/','<span style="color:#910202;">A#</span></a>',$content);

Unfortunately if A#m is the input it only styles the A# part. Any help? The /\b…\b/ method doesn’t appear to work.

Answer 1

The regular expressions work just fine. The problem is that the second one will also match the results of the first!

If you pass in A#m, the first regex will change this to

<span style="color:#910202;">A#m</span></a>

(which is not a valid HTML fragment by the way; what’s that </a> doing there?)

This will then be the input to the second regex. That one will see the A#, replace it and the end result will be

<span style="color:#910202;"><span style="color:#910202;">A#</span></a>m</span></a>

Probably not what you expect.

One solution would be to simply consolidate both expressions into one:

preg_replace('/\b(A#m?)\b/','<span style="color:#910202;">$1</span></a>',$content);

Update: If you want to make a regular expression that recognizes many different chords, use alternation:

preg_replace('/\b(A#(maj7|sus2|sus4)?)\b/',
             '<span style="color:#910202;">$1</span>',
             $content);

Short explanation of (A#(maj7|sus2|sus4)?) so that you can extend it: This regex matches A# alone or optionally (due to the ?) followed by one of (due to the |s) maj7, sus2, sus4. I don’t know what all the options are for chords, but it’s a good idea to read up on that reference/tutorial I link to. Learning just the basics gives you a lot of power to use.