Retrieve number from the string pattern using regular expression

Question

I have a string "Search result:16143 Results found", and I need to retrieve 16143 out of it.

I am coding in ruby and I know this would be clean to get it using RegEx (as oppose to splitting string based on delimiters)

How would I retrieve the number from this string in ruby?

Are you confident that the number will be non-negative, will not contain any non-numeric numbers, and will not be in exponential notation? — Andrew Grimm, Mar 29 '09 at 23:47

score 14 · Answer 1 · answered Mar 29 '09 at 16:28

14

> foo = "Search result:16143 Results found"
=> "Search result:16143 Results found"
> foo[/\d+/].to_i
=> 16143

answered Mar 29 '09 at 16:28

This is the preferred way to extract from a string based on a regex pattern. – Sim Nov 22 '15 at 09:07

LaserJesus · Accepted Answer · 2009-03-29T06:15:05.057

2

I'm not sure on the syntax in Ruby, but the regular expression would be "(\d+)" meaning a string of digits of size 1 or more. You can try it out here: http://www.rubular.com/

Updated: I believe the syntax is /(\d+)/.match(your_string)

edited Mar 29 '09 at 06:15

answered Mar 29 '09 at 06:02

LaserJesus

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note that putting the \d+ in brackets actually captures the value, rather than just returning true or false in relation to the match – LaserJesus Mar 29 '09 at 06:04
Don't forget to convert it to an integer (Neither Integer(foo) nor foo.to_i is perfect, but I'd suggest to_i if you *know* that it is a number). – Andrew Grimm Mar 29 '09 at 23:44

score 1 · Answer 3 · answered Mar 29 '09 at 06:01

1

This regular expression should do it:

\d+

answered Mar 29 '09 at 06:01

Spire

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score 1 · Answer 4 · answered Mar 29 '09 at 09:54

1

For a non regular-expression approach:

irb(main):001:0> foo = "Search result:16143 Results found"
=> "Search result:16143 Results found"
irb(main):002:0> foo[foo.rindex(':')+1..foo.rindex(' Results')-1]
=> "16143"

answered Mar 29 '09 at 09:54

Gdeglin

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score 1 · Answer 5 · answered Mar 29 '09 at 14:48

 # check that the string you have matches a regular expression
 if foo =~ /Search result:(\d+) Results found/
   # the first parenthesized term is put in $1
   num_str = $1
   puts "I found #{num_str}!"
   # if you want to use the match as an integer, remember to use #to_i first
   puts "One more would be #{num_str.to_i + 1}!"
 end

score 0 · Answer 6 · answered Dec 13 '16 at 06:30

0

> foo = "Search result:16143 Results found"
=> "Search result:16143 Results found"
> foo.scan(/\d/).to_i
=> 16143

answered Dec 13 '16 at 06:30

przbadu

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Retrieve number from the string pattern using regular expression

6 Answers6

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