How do you create optional arguments in php

Question

In the PHP manual  to show the syntax for functions with optional parameters  they use brackets around each set of dependent optional parameter  For example  for the date   function  the manual reads   string date   string  format    int  timestamp   time         Where  timestamp is an optional parameter  and when left blank it defaults to the time   function s return value   How do you go about creating optional parameters like this when defining a custom function in PHP

User · Answer

The date function would be defined something like this:

function date($format, $timestamp = null)
{
    if ($timestamp === null) {
        $timestamp = time();
    }

    // Format the timestamp according to $format
}

Usually, you would put the default value like this:

function foo($required, $optional = 42)
{
    // This function can be passed one or more arguments
}

However, only literals are valid default arguments, which is why I used null as default argument in the first example, not $timestamp = time(), and combined it with a null check. Literals include arrays (array() or []), booleans, numbers, strings, and null.

User · Answer

If you don t know how many attributes need to be processed  you can use the variadic argument list token      introduced in PHP 5 6  see full documentation here    Syntax   function  lt functionName gt     lt type gt       lt  paramName gt        For example   function someVariadricFunc     arguments      foreach   arguments as  arg           do some stuff with  arg           someVariadricFunc                 an empty array going to be passed someVariadricFunc  apple          provides a one-element array someVariadricFunc  apple    pear    orange    banana      As you can see  this token basically turns all parameters to an array  which you can process in any way you like

User · Answer

Give the optional argument a default value    function date   format   timestamp

User · Answer

Much like the manual  use an equals     sign in your definition of the parameters   function dosomething  var1   var2   var3    somevalue           Rest of function here

User · Answer

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

User · Answer

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

[php] How do you create optional arguments in php?

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