REGEX: \d not working

Question

I have a text:

Wheels – F/R_ Schwalbe TABLE TOP/Schwalbe Black Jack 26x2.2

And regex to parse wheels size from that string:

/.*Wheels.*(\d*)x/

But it does not work. Besides, when i'm removing asterisk from regex, i'm getting number 6 as group match.

@PavneetSingh , working, but could you please explain where was my mistake and format that as an answer, so i can accept it. — Src
– Src, Commented Feb 15, 2017 at 17:44
Just to clarify, you want to select 'Wheels' from the string and nothing else? — Joshua Kleveter
– Joshua Kleveter, Commented Feb 15, 2017 at 17:45

Community · Accepted Answer · 2017-05-23 11:53:15Z

4

You need to make your .* before the digits lazy instead of greedy:

/.*Wheels.*?(\d*)x/

The .* will greedily consume everything up to the x, leaving nothing for the following \d*. Since * can validly match zero characters, an empty match for \d* is not an incorrect result.

By adding a ? to make a lazy .*? expression, it will try match as few characters as possible, allowing the following \d* to match all the numbers before the x.

edited May 23, 2017 at 11:53

CommunityBot

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answered Feb 15, 2017 at 17:47

apsillers

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2 Comments

Src Over a year ago

Thank you for the explanation!

vaultsort.com Over a year ago

Wow great explanation, I finally understand what lazy means in regex!

Pavneet_Singh · Accepted Answer · 2017-02-15 17:56:49Z

2

You need to make your regex non-greedy because .* will consume your digits and \d* mean zero or no match

.*Wheels.*?(\d*)x

.*? mean match as many characters as few time as possible to stop .* to consume your digits

Follow this Demo for example

Alternately you can make it more efficient if there are no digits after Wheel and your desired values with following regex

.*Wheels[^\d]*(\d*)x

where [^\d]* mean matches anything except digits

edited Feb 15, 2017 at 17:56

answered Feb 15, 2017 at 17:49

Pavneet_Singh

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2 Comments

Src Over a year ago

Thank you for the explanation!

Pavneet_Singh Over a year ago

@Src i am glad that i could help , happy coding

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