Optional Parameters in Custom functions..

Orc · 12-21-2007, 03:59 PM

Is there a way that you can have optional Parameters of a custom function? As if there was an Optional offset for that custom function for whatever it may be?

Tanax · 12-21-2007, 04:07 PM

You can pre-define variables in functions.

PHP Code:


			
function intro($name, $age, $country = 'Sweden', $job = 'student') {

echo 'Hello, my name is '.$name.'! I am a '.$age.' year old '.$job.' from '.country;

}

PHP Code:


			
intro('Marcus', 18);

Code:

Hello, my name is Marcus! I am a 18 year old student from Sweden

But optionally, you could add:

PHP Code:


			
intro('Marcus', 18, 'Norway', 'fisher');

Code:

Hello, my name is Marcus! I am a 18 year old fisher from Norway

xenon · 12-21-2007, 04:12 PM

But if you don't need the parameters to have pre-set values, just use nulls. As in:

Code:

function with_custom_params( $param1, $optional1 = null, $optional2 = null)
{ function body }

However, you can't 'skip' optional parameters. considering the previous defined function, you can call:

Code:

with_custom_params( 'param1', 'param2' );
// or
with_custom_params('param1');

, but you can't do this:

Code:

with_custom_params( 'param1', , 'param3'); // will throw a parsing error

Orc · 12-21-2007, 04:30 PM

Quote:

Originally Posted by xenon

But if you don't need the parameters to have pre-set values, just use nulls. As in:

Code:

function with_custom_params( $param1, $optional1 = null, $optional2 = null)
{ function body }

However, you can't 'skip' optional parameters. considering the previous defined function, you can call:

Code:

with_custom_params( 'param1', 'param2' );
// or
with_custom_params('param1');

, but you can't do this:

Code:

with_custom_params( 'param1', , 'param3'); // will throw a parsing error

Yeah using nulls popped up in my head after I made this thread :p but Tanax has a point as well! :D Terrific!

Alan @ CIT · 12-29-2007, 11:07 PM

Another handy little trick is to use func_get_args() and func_num_args(). These are useful when you don't know how many arguments will be passed to a function.

PHP: func_get_args - Manual
PHP: func_num_args - Manual

Alan