CODEWITHSUNDEEP
regex
MistyD
MistyD

Reputation: 17253

Purpose of this dash character in Regex capture

I am trying to understand the purpose of - in this regex capture clause

(?P<slug>[\w-]+)

This is what I came up for when search for a dash

A dash (-) can be used to specify a range. So the dash is a metacharacter, but only within a character class.If you want to use a literal dash within a character class, you should escape it with a backslash, except when the dash is the first or last character of the character class. So, the regexp [a-z] is equal to [az-] and [-az], they will match any of those three characters.

My questions is what is the - after \w

Upvotes: 0

Views: 141

Answers (1)

Tim Biegeleisen
Tim Biegeleisen

Reputation: 522741

You are looking at what my former CS professor would refer to as a rabbit (out of a hat):

(?P<slug>[\w-]+)

The reason it is a rabbit is because normally your research is correct and dash is used as a part of a range of characters. But in this case, the dash is a literal dash, since it appears at the end of the character class.

So here [\w-]+ means to match one or more word characters or literal dashes.

If you want to include a literal dash in a character class, a safer way is to escape it:

[\w\-]+

Then, the dash may be placed anywhere in the class.

Upvotes: 1

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