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func_num_args() and func_get_arg()

func_num_args() and func_get_arg() are both very useful and powerful function that can be called from user defined functions.
Now these examples are taken from the php.net

<?
function foo()
{
    $numargs = func_num_args();
    echo "Number of arguments: $numargs";
}
foo(1, 2, 3);    // Prints 'Number of arguments: 3'
?>

The example should be pretty intuitive but if not, let me explain. func_num_args() returns the number of variable number of arguments that were passed to a function. Like the in he above example three arguments were passed to function foo.

<?
function foo()
{
     $numargs = func_num_args();
     echo "Number of arguments: $numargs";
     if ($numargs = 2) {
         echo "Second argument is: " . func_get_arg(1) . "n";
     }
}
foo (1, 2, 3);
?>

In this example func_get_arg gets a copy of the “ith” variable number of argument.
Now if you combine these two functions, you can create something like this.

<?
function append_default(&$obj)
{
	$default = func_get_arg(1);
	for($i = 2, $total = func_num_args(); $i < $total; $i++)
		$obj->{func_get_arg($i)} = $default;
}
append_default($some_obj, "0", "age", "height", "weight");
?>

In this example, you can call function on some object and have default values appended to its member variables. In this example the $some_obj will have its age, height, weight, member variables get a default value of “0″. This works because func_get_arg(1) will return a copy of the first variable number of argument. This is important to not because you can’t pass a reference to an object to as variable like above. This is why the append_default explicitly requires a reference to an object. Also notice a good php performance speed up technique in the above code. It is inefficient to have to recompute func_num_args at every loop. Rather it is better practice, to save the result of the function like in the above code.