add a note
if the value of the argument within the function is changed, it does not get changed outside of the function.
$a=10;
$b=13;
function add($a,$b){
echo "The Sum of $a+$b= ", $a+$b, "<br />";
$a=5;
$b=10;
echo "The sum is=" ,$a+$b , "<br />" ; }
add($a,$b);
echo $a+$b;
