Since I am pulling most of my content from other sites such as Mahalo and Quora I thought I would pull back some of my more interesting HN comments.

Can anyone explain how this regex [- ~] matches ASCII characters?

It’s pretty simple. Assuming you know regex. Im going to assume you don’t since you are asking.

The bracket expression [ ] defines single characters to match, however you can have more then 1 character inside which all will match.

[a] matches a
[ab] matches either a or b
[abc] matches either a or b or c
[a-c] matches either a or b or c

The – allows us to define the range. You can just as easily use [abc] but for long sequences such as [a-z] consider it short hand.

In this case [ -~] it means every character between and , which just happens to be all the ASCII printable characters (see chart in the article). The only bit you need to keep in mind is that is a character as well, and hence you can match on it.

You could rewrite the regex like so (note I haven’t escaped or anything in this so its probably not valid)

[ !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~]

but that’s not quite as clever or neat.