Question

So, I am writing a short (and simple) regular expression, but I can think of two possible ways to do it. They both seem like good conventions, but I am not sure which one is better.

What I want to achieve with this pattern (ordered hierarchically):

• Speed
• Readability
• Sexyness

The regexp needs to match for one of two characters(let’s say they are # and ~) at the beginning of each line:

• ^[#~]
• ^(#|~) Edit: since ^#|~ didn’t do what I wanted it, I corrected it.

I like both of them for different reasons (out of which most are aesthetic reasons); the bonus with the second one is that it’s a byte shorter.

Thanks!

Answer 1

^#|~ is not the same as ^[#~]. ^#|~ will match a ~ in the middle of the string because | has a lower precedence than ^. The correct way to express that is ^(?:#|~) or ^(#|~) if you don’t mind about the extra capture group.

Comparing ^[#~] to the corrected regex ^(?:#|~), I’d say the former totally wins out. (Normally a character class is more efficient than | because the latter is less specialized.)