CODEWITHSUNDEEP
phpregexpreg-match
Ilia Ross
Ilia Ross

Reputation: 13412

Preg_match cuts last zeros from some numbers

I think it only happens when I write a regex. I have a simple regex to validate a set of pagination numbers, that later will be submitted to database, like 5, 10, 25, 50, 100, 250 example:

/all|5|10|25|50|100|250/

When I perform a test, my regex above cuts 0 only from numbers 50, 100 and 250 but not from 10!!?

Online example:
http://viper-7.com/IbKFKw

What am I doing wrong here? What am I really missing this time?

Upvotes: 3

Views: 117

Answers (2)

Martin Ender
Martin Ender

Reputation: 44279

The alternatives are tried from left to right, so matching 5 takes precedence over 50. But there's no 1 to cut off the 0 from 10. You can simply reorder them:

/all|250|100|50|25|10|5/

Alternatively, add the 0 optionally to the relevant alternatives (and since ? is greedy, the 0 will be matched if present):

/all|50?|100?|250?/

or

/all|(?:5|10|25)0?/

If this is not for matching but for validation (i.e. checking against the entire string), then go with Jerry's suggestion and use anchors to make sure that there are no undesired characters around your number:

/^(?:all|5|10|25|50|100|250)$/

(Of course inside (?:...) you could also use any of my above patterns, but now precedence is irrelevant because incomplete matches are disallowed.)

Upvotes: 7

Jerry
Jerry

Reputation: 71568

This is because in the string 50, the regex first matches 5, which is valid. In the string 250, the regex first matches 25, which is valid and ends here.

You might try adding anchors:

/^(?:all|5|10|25|50|100|250)$/

This forces the regex to match the whole string, and hence, return the correct match you are looking for.

Upvotes: 10

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