CODEWITHSUNDEEP
rubyregexliterals
rhys97
rhys97

Reputation: 81

What are `\.` and `i` in a regular expression?

Could someone tell me what the \. and i on the :with-line in the following are used for?

validates :image_url, allow_blank: true, format: {
    with:    %r{\.(gif|jpg|png)\Z}i,
    message: 'must be a URL for GIF, JPG or PNG file.'
}

Upvotes: 4

Views: 231

Answers (2)

Justin Wood
Justin Wood

Reputation: 10051

%r{} is used for regular expressions.

\. is looking for the literal character .. You need the \ to escape because just using . means something else entirely (any character matches).

i is used for case insensitive searches.

Essentially, your regex is matching for anything that ends in .gif, .jpg or .png. These could also be something like .GiF because of the case insensitive search.

Upvotes: 7

Arup Rakshit
Arup Rakshit

Reputation: 118261

In Ruby, you can create Regexps using the %r{...} literals.

The following are metacharacters (, ), [, ], {, }, ., ?, +, *. They have a specific meaning when appearing in a pattern. To match them literally they must be backslash-escaped.

i is for case insensitive match.

Upvotes: 7

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