custom functions, is there a way to set an optional parameter?

helz

i have several functions that have optional parameters.
is there a way to set these as option so i do not get warning errors in php saying missing parameters?

Installer

function my_function($parameter, $optional_parameter = true)

("true" can be replaced with whatever value you need.)

See "Default argument values" on this page.

helz

ok, could i set it to something like:
function my_function($parameter, $optional_parameter = "")
or:
function my_function($parameter, $optional_parameter = null)

=edit=

ah yes = NULL

Installer

Yes, you could do it like that, then call it like this:

my_function($var1, $var2)
// or
my_function($var1)

helz

superb
that helps alot
thanks!

helz

if i wanted a parameter to be a must, so if it doesnt exist then don't carry on with the function would this work?

function CusFunc($requiredparameter) {
   if (!isset($requiredparameter)) {
      exit();
   } else {//carry on with function

   }
}

Installer

Your code would work, but only if the calling expression is either "CusFunc(NULL)" or "CusFunc()". In the second case the interpreter will issue a warning and the missing parameter will evaluate to NULL. Code should be written so that the second case doesn't happen, anyway.

helz

oh, dont fully understand but ah well.

something like this then?

function($var) {
   if (!$var) exit();
   else {
      //code here
   }
}

Installer

That will work too, although "!$var" will evaluate to different boolean values with various values of "$var" than "isset($var)" will. There's are good charts of value-checking methods and their results here.

The functions you posted would be better-used to validate a variable before passing it to the data manipulation function, rather than inside that function itself.

helz

ah
i was just wondering how php does it with the built-in functions of php, and was hoping to be able to replicate that with custom functions

Weedpacket

You might also want to look at the function-handling functions ([man]func_get_args[/man] and co.), that will allow access to all of the arguments passed to the function, however many there were (as can be done with [man]sprintf[/man] and the other functions with "[mixed, ...]" in their signatures).

Using those functions you can find out how many arguments were passed, get any argument in that collection, get the whole lot in an array and, with the variable-handling functions, find out what types they were. With all that information in hand, your code can then decide how to deal with each case (as in, for example, the way you can pass strings or arrays to [man]str_replace[/man]).