PHP function overloading

Question

Coming from C++ background ;)
How can I overload PHP functions?

One function definition if there are any arguments, and another if there are no arguments? Is it

Answer 1

";
        }

        else if($arg1 != null && $arg2 != null && $arg3 != null)
            {
            $volume=$arg1*$arg2*$arg3;
            echo "volume of a cuboid ".$volume ."
";
            }
            else if($arg1 != null && $arg2 != null)
            {
            $area=$arg1*$arg2;
            echo "area of square  = " .$area ."
";
            }
            else if($arg1 != null)
            {
            $volume=$arg1*$arg1*$arg1; 
            echo "volume of a cube = ".$volume ."
";
            }


        }


    }

    $obj=new abs();
    echo "For no arguments. 
";
    $obj->volume();
    echo "For one arguments. 
";
    $obj->volume(3);
    echo "For two arguments. 
";
    $obj->volume(3,4);
    echo "For three arguments. 
";
    $obj->volume(3,4,5);
    ?>