Regular expressions in Ruby

Ruby
1

I’m new to Ruby, and just want to ask about how to read the following
statement from the “Agile Web D. With Rails, 3rd edition” book:

%r{.(gif|jpg|png)$}i

I knew that %r is a way to write a regular expression.

But, what is the $, and the i?

Thanks.

2

Abder-rahman Ali wrote:

%r{.(gif|jpg|png)$}i

I knew that %r is a way to write a regular expression.

But, what is the $, and the i?

http://www.ruby-doc.org/docs/ProgrammingRuby/html/language.html#UK

3

Brian C. wrote:

Abder-rahman Ali wrote:

%r{.(gif|jpg|png)$}i

I knew that %r is a way to write a regular expression.

But, what is the $, and the i?

Programming Ruby: The Pragmatic Programmer's Guide

Thanks Brian.

4

On Mon, Jun 14, 2010 at 5:24 PM, Abder-rahman Ali
[email protected] wrote:

I’m new to Ruby, and just want to ask about how to read the following
statement from the “Agile Web D. With Rails, 3rd edition” book:

%r{.(gif|jpg|png)$}i

I knew that %r is a way to write a regular expression.

But, what is the $, and the i?

I always have this link handy:

$ matches the end of a line or string
i is a modifier that makes the regexp case insensitive.

Jesus.

5

On Mon, Jun 14, 2010 at 10:24 AM, Abder-rahman Ali <
[email protected]> wrote:

I’m new to Ruby, and just want to ask about how to read the following
statement from the “Agile Web D. With Rails, 3rd edition” book:

%r{.(gif|jpg|png)$}i

It matches a dot, followed by either gif or jpg or png, at the end of
the
string. It does not care about case.

For example, it would match

foo.gif
foo.GiF
fOoO.jpg
bar.PNG

It would not match

foogif
foo.gif.
foo.giff
foo.jp
foo.pjg
foo.jpx
foo.jpg.csv

6

On Mon, Jun 14, 2010 at 12:24 PM, Abder-rahman Ali
[email protected] wrote:

I’m new to Ruby, and just want to ask about how to read the following
statement from the “Agile Web D. With Rails, 3rd edition” book:

%r{.(gif|jpg|png)$}i

I knew that %r is a way to write a regular expression.

But, what is the $, and the i?

$ matches the end of the string and i makes the search case
insensitve. This is not Ruby specific, perphaps you should read about
regular expressions. See Ruby Regexp Class - Regular Expressions in Ruby

Bye

7

After referring to the regular expressions references provided, test
them out at rubular.com.

8

But, what is the $, and the i?
→ http://rubular.com/ → Regex quick reference

The \ escapes the . Thus . matches the ‘.’ character.

Marc W.

9

I suppose this shall help

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On Mon, Jun 14, 2010 at 8:54 PM, Abder-rahman Ali <