How do you create optional arguments in php?

Question

In the php manual they describe functions like so:

string date ( string $format [, int $timestamp ] )

How would this function look when you define it?

Answer 1

function dosomething($var1, $var2, $var3='somevalue'){
..
}

Answer 2

Give the optional argument a default value.

function date ($format, $timestamp='') {
}

Answer 3

Some notes that I also found useful:

• Keep your default values on the right side.

  function whatever($var1, $var2, $var3="constant", $var4="another")

• The default value of the argument must be a constant expression. It can't be a variable or a function call.

Answer 4

The default value of the argument must be a constant expression. It can't be a variable or a function call.

If you need this functionality however:

function foo($foo, $bar = false)
{
    if(!$bar)
    {
        $bar = $foo;
    }
}

Assuming $bar isn't expected to be a boolean of course.