I’m working on a regex to match this set of numbers:

xxxx xxx xxxx
01 xxx xxxx
 234 1 xxx xxxx
xxxx-xxx-xxxx
xxxxxxxxxxx
234 xxx xxx xxxx
234(xxx)xxx-xxxx
234(xxx)xxx xxxx
 234(xxx)xxx xxxx
 234(xxx) xxx xxxx
 234(xxx)xxx-xxxx
234xxxxxxxxxx
 234xxxxxxxxxx

The rules are:

• At most 11 digits long (any number combo, excluding the static parts)
• Optional (234) or ( 234)
• Optional 1 or 01 or 234 1
• Optional bracketing as specified above.

It’s to validate the Nigerian phone numbering system. I have searched far and wide and haven’t seen any good solutions so far.

I have this expression:

/^(\ )?234[0-9]*?.*/gm

but it doesn’t match the ones without (234) properly.

Specifically:

xxxx xxx xxxx
01 xxx xxxx
xxxx-xxx-xxxx
xxxxxxxxxxx

How can I make this work? I’m kinda new to regex, would appreciate any assistance I can get.

Demo

CodePudding user response：

With something as simple as:

$output = trim(filter_var($input, FILTER_SANITIZE_NUMBER_INT), ' ');  

You will only be left with digits. Now you might want to remove several optional starts:

$output = preg_replace('/^0|^01|^234|^2341/', '', $input);

And finally you may want to check if the length is valid.

This does not invalidate a number like ' 234(123) (456) 7890', but should it? After all, you can only dial numbers.

CodePudding user response：

You can use

^(?:(?:(?:\ ?234(?:\h1)?|01)\h*)?(?:\(\d{3}\)|\d{3})|\d{4})(?:\W*\d{3})?\W*\d{4}$

See the regex demo. Details:

• ^ - start of a string
• (?:(?:(?:\ ?234(?:\h1)?|01)\h*)?(?:\(\d{3}\)|\d{3})|\d{4}):
  • (?:(?:\ ?234(?:\h1)?|01)\h*)? - an optional occurrence of
    • (?:\ ?234(?:\h1)?|01) - an optional and then 234 optionall followed with a horizontal whitespace and 1, or 01
    • \h* - zero or more horizontal whitespaces
  • (?:\(\d{3}\)|\d{3})| - (, three digits, ) or three digits, or
  • \d{4} - four digits
• (?:\W*\d{3})? - an optional sequence of zero or more non-word chars and then 3 digits
• \W* - zero or more non-word chars
• \d{4} - four digits
• $ - end of the string.

To match the phone numbers anywhere in a longer string use

(?:(?:(?:\ ?234(?:\h1)?|01)\h*)?(?:\(\d{3}\)|\d{3})|\d{4})(?:\W*\d{3})?\W*\d{4}(?!\d)

See the regex demo.