PHP versions prior to 4.0.6 modified the passed array itself and converted strings to numbers (which most of the time converted them to zero, depending on their value).
?php $a = array( 2,4,6,8); echo "somme(a) = ".array_sum($a) ."\n"; / / affiche: somme(a) = 20 $b = array("a"= 1.2 ,"b"= 2.3 ,"c"= 3.4); echo "somme(b) = ".array_sum($b) ."\n"; / / affiche: somme(b) = 6.9?