PHP filter array

Question

I have a PHP array of strings. The strings are supposed to represent PIN codes which are of 6 digits like:

560095

Having a space after the first 3 digits is also considered valid e.g. 560 095.

Not all array elements are valid. I want to filter out all invalid PIN codes.

Answer 1

Yes you can make use of regex for this.

PHP has a function called preg_grep to which you pass your regular expression and it returns a new array with entries from the input array that match the pattern.

$new_array = preg_grep('/^\d{3} ?\d{3}$/',$array);

Explanation of the regex:

^     - Start anchor
\d{3} - 3 digits. Same as [0-9][0-9][0-9]
 ?    - optional space (there is a space before ?)
        If you want to allow any number of any whitespace between the groups
        you can use \s* instead
\d{3} - 3 digits
$     - End anchor

Answer 2

Yes, you can use a regular expression to make sure there are 6 digits with or without a space.

A neat tool for playing with regular expressions is RegExr... here's what RegEx I came up with:

^[0-9]{3}\s?[0-9]{3}$

It matches the beginning of the string ^, then any three numbers [0-9]{3} followed by an optional space \s? followed by another three numbers [0-9]{3}, followed by the end of the string $.

Passing the array into the PHP function preg_grep along with the Regex will return a new array with only matching indeces.