What are the rules about calling PHP functions with not enough parameters?

I have a function which takes two arguments but I want the second one to be optional:

function myFunction($arg1, $arg2) {
  //blah
  //blah
  if (isset($arg2)) {
    //blah
  } else {
    //blah
  }
}

So when I call it, I might do myFunction("something") or I might do myFunction("something", "something else").

When I only include one argument, PHP gives this warning:

Warning: Missing argument 2 for myFunction(), ...

So it works, but obviously the developers frown upon it.

Is it ok to do this or should I be passing in "" or false or 0 to the second argument when I don't want to use it and testing for that instead of using 开发者_如何学Cisset()?

I've noticed that a lot of people miss out arguments when calling functions in JavaScript which is why I'm asking if it's done in PHP too.

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Its done by setting up some parameters as optional/giving it a default:

function myFunction($arg1, $arg2 = false)

then you can call the function like this:

myFunction('something');

or

myFunction('something', 'something else');

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You can set it in your function declaration:

function myFunction($arg1, $arg2 = NULL) {

This way, the second parameter is optional. Note that the optional parameters have to be at the end, you cannot have any non-optional parameters after them.

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You need to set a default for the argument in the function declaration, like this:

function myFunction($arg1, $arg2 = false) {
  //blah
  //blah
  if (isset($arg2)) {
    //blah
  } else {
    //blah
  }
}

---

function myFunction($arg1, $arg2=null)

http://www.php.net/manual/en/functions.arguments.php#functions.arguments.default

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Define a default value of the parameter in the function:

public function foo($arg1, $arg2 = 'default') {
    //yourfunction 
}