My readers really loved my previous two posts – my favorite regex of all time and my other favorite regex. I was thinking and realized I had yet another favorite regex:
[A-z]
Any idea what this regexp matches? Scroll down for the answer.
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I bet you're not entirely sure because usually you write either [a-z] or [A-Z] or [a-zA-Z] or [A-Za-z]. But here it's [A-z]. A is capital, and z is lowecase. I honestly thought it was a syntax error the first time I saw it. I asked some of my friends and they said it matches all letters A-Z and all letters a-z. But that is not true. It looks like it matches A-Z and a-z but in reality it matches these additional symbols: []^_,`. It turns out that the regex [A-z] is equal to this regex: [A-Z[]^_`a-z].
As always, ASCII table comes to the rescue to help us understand it. A-Z are consecutive, then for some reason some smart-ass decided we need to have these punctuation symbols there, and only then a-z follows. The range [A-z] is colored in blue.
[A-z] matches [A-Z[\]^_`a-z].
See you next time!