Well depends on what kind of data you are validating, a quick example would be to validate a number within a certain range (e.g. Persons age, height, weight, etcetera).
<?php
function range($min,$max,$val)
{
if ($val < $min) || ($val > $max)
return 1; //Error, invalid data
else
return 0; //data validate properly
}
?>
Unsolved 
