Question

What’s the easiest way to format a string based on another input string that uses hash symbols, minus, and spaces.

What I have is one string that contains a phone number that might look like this (or has multiple spaces in it):

012-34567890

I have another string that contains the format that the number has to be converted to, this looks like this:

### - ## ## ##

or

## - ### ## ##

or

###-## ## ##

The hash positions must be leading for the formatting of the numbers. I can’t seem to think of something that does this…

In some cases (like for international phone numbers) the (, ) and + symbols must be used. In that case the conversion string looks like this (for instance)

+(##)-(#)##-## ## ##

Anyone any ideas?

Answer 1

$number = "012-34567890";
$format1 = "### - ## ## ##";
$format2 = "+(##)-(#)##-## ## ##";
$format3 = "## - ### ## ####";
$format4 = "###-## ## ####";

function formatNumber($number, $format)
{
    // get all digits in this telephone number
    if (!preg_match_all("~\w~", $number, $matches))
        return false;

    // index of next digit to replace #
    $current = 0;

    // walk though each character of $format and replace #
    for ($i = 0; $i < strlen($format); $i++)
        if ($format[$i] == "#")
        {
            if (!isset($matches[0][$current]))
                // more # than numbers
                return false;

            $format[$i] = $matches[0][$current++];
        }

    if (count($matches[0]) != $current)
        // more numbers than #
        return false;

    return $format;
}

var_dump(
    formatNumber($number, $format1),
    formatNumber($number, $format2),
    formatNumber($number, $format3),
    formatNumber($number, $format4)
);

Outputs

boolean false

string '+(01)-(2)34-56 78 90' (length=20)

string '01 - 234 56 7890' (length=16)

string '012-34 56 7890' (length=14)

If you have got more # than digits, you could just remove them instead of having the the function return false. If you have more digits than # you could also append them to the format.