note 84860 modified in function.abs by danbrown

[EDIT by danbrown AT php DOT net: Merged two posts by the same author.] This is a note to concordia's comment at http://us.php.net/manual/en/function.abs.php#58508 I believe there is an easier way to turn a positive number into a negative one and vice versa in one line: <?php function change_pol($integer){ return (0 - $integer); } ?> It takes another additional line to check if it's really a number: <?php function change_pol($integer){ if(!is_numeric($integer)){ return false; } return (0 - $integer); } ?> Keep in mind that if I do 0 - -5 (given that $integer is -5), it will turn into +, thus turning the result into +5. Works like a charm for me. Input like '-5' will work as well (as PHP turns strings automatically into an integer or float), even '-.9' will return as 0.9. Another thing I'd like to note is that the variable name $integer used in my examples aren't really advised as the function goes beyond simple integers. Initially, I used this function only for the handling of integers, hence the variable name. It is only later that I've discovered it goes beyond integers. 0 will also return to 0 (if that shouldn't be obvious). Perhaps it is better to make it return NULL instead of FALSE when it fails the is_numeric condition, so that there's no mix with the function's result to be false instead of actually 0, however only checking with '===' instead of '==' should solve this, I believe. --was-- This is a note to concordia's comment at http://us.php.net/manual/en/function.abs.php#58508 I believe there is an easier way to turn a positive number into a negative one and vice versa in one line: <?php function change_pol($integer){ return (0 - $integer); } ?> It takes another additional line to check if it's really a number: <?php function change_pol($integer){ if(!is_numeric($integer)){ return false; } return (0 - $integer); } ?> Keep in mind that if I do 0 - -5 (given that $integer is -5), it will turn into +, thus turning the result into +5. Works like a charm for me. Input like '-5' will work as well (as PHP turns it automatically into a string or float), even '-.9' will return as 0.9 . http://php.net/manual/en/function.abs.php