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Convert mobile number to international format dynamically with php

David Carr

PHP & MySQL Tutorials

    I often need to covert mobile numbers into a UK international format of 44 followed by the number such as 442548951486 the numbers I work with can be in a mixed format some without a starting 0 others with 44 and same with spaces, so I wrote function that will convert a number in any mixture into a standard format quick and easily and as all the code is inside a function is reusable which means converting numbers in bulk is now very easy to do.

    The function simple needs a number passing to it, a check is done to make sure the number only contains numbers then a check is done to see if the number starts with a 0 if not if will add a 0 as long as the start is not 4. Then a check is done to replace the 0 with a 44 then finally any spaces are removed and the formatted number is then returned.

    Here's the function:

    function format_number($number)
        //make sure the number is actually a number
            //if number doesn't start with a 0 or a 4 add a 0 to the start.
            if($number[0] != 0 && $number[0] != 4){
                $number = "0".$number;
            //if number starts with a 0 replace with 4
            if($number[0] == 0){
                $number[0] = str_replace("0","4",$number[0]);
                $number = "4".$number;
            //remove any spaces in the number
            $number = str_replace(" ","",$number);
            //return the number
            return $number;
        //number is not a number
        } else {
            //return nothing
            return false;

    <p>Usage Example:</p>

    echo format_number('07295514973');


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