(PHP 4, PHP 5)
abs — Absolute value
numberThe numeric value to process
   The absolute value of number. If the
   argument number is
   of type float, the return type is also float,
   otherwise it is integer (as float usually has a
   bigger value range than integer).
  
Example #1 abs() example
<?php
echo abs(-4.2); // 4.2 (double/float)
echo abs(5);    // 5 (integer)
echo abs(-5);   // 5 (integer)
?>