PHP REGEX How to verify the exact format of the user input

Question

Regex is not my friend. He would find a good man to help me. User can specify working time in the format: 00:00-12:30 or 00:00-12:30,14:15-18:00

I would therefore need to verify the input complies with the variants, but nothing else should pass. I tried to combine pieces like

[0-9] {2} [0-9] {2}

But I really do not understand: /

You are expected to try to write the code yourself. After doing more research if you have a problem post what you've tried with a clear explanation of what isn't working and provide a Minimal, Complete, and Verifiable example. Read How to Ask a good question. Be sure to take the tour and read this. — Jay Blanchard
– Jay Blanchard, Commented Jul 17, 2017 at 19:05
You can't have the spaces in there like that either. Your regex essentially says 2 numbers followed space with quantity 2...etc. Every character in a regex has meaning, even if it is just that literal character. — Jonathan Kuhn
– Jonathan Kuhn, Commented Jul 17, 2017 at 19:05
Ranges for regex are long and overly complicated. You should add your PHP usage attempt, it is unclear to me if you used [0-9] {2} [0-9] {2} or some parts of that with other code. — chris85
– chris85, Commented Jul 17, 2017 at 19:09
Regex should be used to validate a format, not content. Once you start validating that the numbers are between x and y and more, they get tons more complicated or even likely can't be done at all (for example, comparing that a is less than b). They can be done by much better tools. For example, to validate a number is between 0 and 23, you can either say if($number >= 0 && $number <= 23) or you can use a regex like: /^([01]?[\d|2[0-3])$/. Which would you think is easier to understand? — Jonathan Kuhn
– Jonathan Kuhn, Commented Jul 17, 2017 at 19:10

score 3 · Accepted Answer · 2017-07-17 21:12:07Z

3

Here you go.

((?&hh_mm))-((?&hh_mm))(?:,((?&hh_mm))-((?&hh_mm)))?(?(DEFINE)(?<hh_mm>(?:[01]\d|2[0-3]):[0-5]\d))

https://regex101.com/r/lUQHun/1

Capture groups provided for hh:mm of each part.

Expanded

 ( (?&hh_mm) )                 # (1), hh:mm
 -                             # -
 ( (?&hh_mm) )                 # (2), hh:mm

 (?:                           # Optional 
      ,                             # ,
      ( (?&hh_mm) )                 # (3), hh:mm
      -                             # -
      ( (?&hh_mm) )                 # (4), hh:mm
 )?
 (?(DEFINE)
      (?<hh_mm>                    
           (?: [01] \d | 2 [0-3] )
           :
           [0-5] \d 
      )                            
 )

edited Jul 17, 2017 at 21:12

answered Jul 17, 2017 at 20:20

user557597

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Comments

Graham · Accepted Answer · 2017-09-23 23:12:37Z

You may use

'~^((?:[01]\d|2[0-3]):[0-5]\d)-(?1)(?:,(?1)-(?1))?$~'

See the regex demo

It matches

^ - the start of string
((?:[01]\d|2[0-3]):[0-5]\d) - a capturing group #1 that matches:
- (?:[01]\d|2[0-3]) - either of the two alternatives:
  - [01]\d - 0 or 1 followed with any digit
  - | - or
  - 2[0-3] - 2 followed with a digit from 0 to 3
- : - a colon
- [0-5] - a digit from 0 to 5
- \d - any digit
- - a hyphen
(?1) - the pattern defined inside Group 1
(?:,(?1)-(?1))? - an optional sequence (? at the end makes the regex engine match the patterns inside the non-capturing (?:...) match 1 or 0 times) that matches
- , - a comma
- (?1)-(?1) - Group 1 pattern, - and again Group 1 pattern
$ - end of string

Note that the (?1) is a subroutine call that is used to reuse a part of the pattern inside (...) capturing parentheses. (?1) means take the pattern defined in the first pair of unescaped parentheses in the pattern.

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