PHP - Regex on numbers, optional decimals and letter

Question

I'm trying to "validate" some input from a form on the backend but I kinda got stuck with the required regex. Basically, I want to get a number, no leading zeroes, with an optional decimal and an optional case insensitive thousands notation (1,000 = 1k, 1,000,000 = 1m, 1 billion = 1b ...) These should match/validate:

12.39
12.389k
99.1003b
40.1m

These should fail.

0.0
12.00b
1e3
2^5
0xFF
12.6z
asdf

So far I've tried this:

^[1-9]\d*(?:\.\d+)?(?:[kmbt])?$

It works but I'm thinking maybe someone could solve this a bit more elegantly than I did.

Your regex isn't taking into account thousands notation, is that something you care about? There are no examples in your examples but your description mentions it. or 40.1m is in your string but denotes 40,100,000? — chris85
– chris85, Commented Oct 14, 2016 at 12:53

Casimir et Hippolyte · Accepted Answer · 2016-10-14 13:37:55Z

1

[Edit] without thousand separator:

/^(?:[1-9][0-9]*(?:\.[0-9]*[1-9])?|0\.[0-9]*[1-9])[kbmt]?$/i

demo

[Old answer] with thousand separator:

You can do it with:

/^(?:[1-9][0-9]{0,2}(?:(,?)[0-9]{3})?(?:\1[0-9]{3})*(?:\.[0-9]*[1-9])?|0\.[0-9]*[1-9])[kbmt]?$/i

demo

details:

^
(?: # numbers >= 1
    [1-9][0-9]{0,2}
    (?:(,?)[0-9]{3})? # capture an eventual thousand separator
    (?:\1[0-9]{3})*
    # decimal
    (?:\.[0-9]*[1-9])?

  | # numbers < 1
    0\.[0-9]*[1-9]
)[kbmt]?$

edited Oct 14, 2016 at 13:37

answered Oct 14, 2016 at 13:07

Casimir et Hippolyte

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5 Comments

Alexander Holman Over a year ago

Thats a huge number of steps... and will only match on new line will it not?

Casimir et Hippolyte Over a year ago

@AlexanderHolman: the pattern is designed for a whole string (as the pattern example in the question). The goal is to valid, not to extract. The number of steps is low, about 20 for a valid string and about 25 for an invalid string, it's few.

the_architecht Over a year ago

the one without the thousand separator works like a charm. Thank you! Just can't really figure out why the one from @ShekharKhairnar link works

Alexander Holman Over a year ago

@Casimir et Hippolyte my bad, I missed the "validate"

the_architecht Over a year ago

@CasimiretHippolyte yep, just noticed that right now after a few test cases. Oh well, it was short and sweet xD

Community · Accepted Answer · 2020-06-20 09:12:55Z

0

Update in REGEX.

Below regex will not leading zero allow special characters and characters without specified for notation.

Below regex will allow decimal and integer with thousand and other notation.

^[1-9]\d*(\.[0-9]+)?(?:[kmbtKMBT])?$

Please check working demo : http://www.regexpal.com/?fam=95995

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Oct 14, 2016 at 12:47

Rahul Patel

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1 Comment

the_architecht Over a year ago

This will match 12.00 which is not really desired. Thanks

Alexander Holman · Accepted Answer · 2016-10-14 13:17:01Z

0

The below should be what you're after:

/(\b[1-9][\d\,\.]+([kmbt]?))(\s)/g

It matches 12.00b however... Here is an example of it's use.

Group 1 will contain your exact match.

edited Oct 14, 2016 at 13:17

answered Oct 14, 2016 at 13:09

Alexander Holman

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1 Comment

the_architecht Over a year ago

works, but as stated matches 12.00b which I'm trying to avoid altogether.

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