CODEWITHSUNDEEP
regex
maxp
maxp

Reputation: 25141

Simple Regex, match any string with at least one hyphen

I'm a bit puzzled with a particular regex that is seemingly simple.

The match must be a string with only a-z, A-Z, 0-9 and must have at least one occurence of the '-' character anywhere in the string.

I have [a-zA-Z0-9-]+ but the problem is, it will also match those without the '-' character.

ABC123-ABC //should match

ABC123ABC //shouldn't match.

Upvotes: 13

Views: 29809

Answers (3)

ridgerunner
ridgerunner

Reputation: 34395

Peter's solution: (^([a-zA-Z0-9]*-[a-zA-Z0-9]*)+$) performs well when given a string that matches. However, this expression experiences Catastrophic Backtracking when presented with a non-matching string such as:

aa-aa-aa-aa-aa-aa-aa-aa-aa-aa-aa-aa%

Here are regular expressions which avoid this problem:

^[a-zA-Z0-9]*-[-a-zA-Z0-9]*$ # Match one or more -

^([a-zA-Z0-9]*-){5}[a-zA-Z0-9]*$ # Match exactly 5 -

^([a-zA-Z0-9]*-){1,5}[a-zA-Z0-9]*$ # Match from 1 to 5 -

Upvotes: 4

Petar Ivanov
Petar Ivanov

Reputation: 93030

This should work:

^([a-zA-Z0-9]*-[a-zA-Z0-9]*)+$

Also if you want to have exactly 135 hyphens:

^([a-zA-Z0-9]*-[a-zA-Z0-9]*){135}$

or if you want to have at least 23 hyphens but not more than 54 hyphens:

^([a-zA-Z0-9]*-[a-zA-Z0-9]*){23,54}$

You get the point :)

Upvotes: 31

Bohemian
Bohemian

Reputation: 425033

Here's a simple regex:

^(?=.*-)[a-zA-Z0-9-]+$

Upvotes: 2

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