CODEWITHSUNDEEP
regex
Mario Bumbera
Mario Bumbera

Reputation: 1

regex how to define that the rule must be the same

I am searching for a number in this format.

[0-9]{3,6}[\-\/]{1}[0-9]{1,3}[\-\/]{1}[0-9]{1,2}

Is there a way how to define that there should be always only slash/ or colom- ? In other words, option that first one is - and the second one / should be omitted.

Upvotes: 0

Views: 34

Answers (3)

Casimir et Hippolyte
Casimir et Hippolyte

Reputation: 89584

You can also use an alternation:

[0-9]{3,6}(-[0-9]{1,3}-|\/[0-9]{1,3}\/)[0-9]{1,2}

It's a basic idea but it works.

Upvotes: 0

Bohemian
Bohemian

Reputation: 425238

The general solution to this is to leave for basic regex as-is, but add a look ahead to assert various over-arching requirements:

^(?!.*-.*/|.*/.*-)[0-9]{3,6}[\-\/]{1}[0-9]{1,3}[\-\/]{1}[0-9]{1,2}

The (negative) look ahead (?!.*-.*/|.*/.*-) means "in the following input, there is neither a - then a /, or a / then a -.

Although you could probably do it without a look ahead, it's easier to understand with a look ahead, plus you can add as many of these as you need as other requirements come along.

Upvotes: 0

ssc-hrep3
ssc-hrep3

Reputation: 16089

Yes, you can use the \1 back-reference. This matches the same character (or group) as the first matching group. In this case, the ([-\/]) is the first matching group and \1 requires to be the same character.

[0-9]{3,6}([-\/])[0-9]{1,3}\1[0-9]{1,2}

Here is an example: https://regex101.com/r/mKxnUN/1

Upvotes: 1

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