passing by reference or keyword global?

Hello,

just "stumbled" this way of function parameter passing inside the PHP manual (yes, there are still things I never used in php )

Code:

<?php
function add_some_extra(&$string)
{
   $string .= 'and something extra.';
}
$str = 'This is a string, ';
add_some_extra($str);
echo $str;    // outputs 'This is a string, and something extra.'
?>

I used this kind of code to get the value inside a faunction:

Code:

<?php
function add_some_extra() 
{
   global $string;
   $string .= 'and something extra.';
}
$string = 'This is a string, ';
add_some_extra(); 
echo $string;   // outputs 'This is a string, and something extra.'
?>

which is the better way?

EDIT: fixed the second example...

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Both ways do the exact same thing.

The first is good when you work with objects, as the second wont work inside of an object.

yes, right inside objects I use "$this" to access variables. What you're syaing is about this?

Code:

<?php
class foo() {
function add_some_extra(&$string) {
   $string .= 'and something extra.';
}
}
$str = 'This is a string, ';
$obj = new foo;
$obj->add_some_extra($str);
echo $str;    // outputs 'This is a string, and something extra.'
?>

What you're syaing is about this?

Code:

<?php
class foo() {
function add_some_extra(&$string) {
   $string .= 'and something extra.';
}
}
$str = 'This is a string, ';
$obj = new foo;
$obj->add_some_extra($str);
echo $str;    // outputs 'This is a string, and something extra.'
?>

there went something wrong while posting the last answer...
this should be an example for "passing function paramaters" within an object, right?

this is the good version:

Code:

<?php
class foo {
function add_some_extra(&$string) {
   $string .= 'and something extra.';
}
}
$str = 'This is a string, ';
$obj = new foo;
$obj->add_some_extra($str);
echo $str;    // outputs 'This is a string, and something extra.'
?>

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That is correct, but I think that in classes you should not use this kind of programming.

I mean if a variable holds something that should be passed by reference to the class then propably it should be a property of the class.

eg :

Code:

<?php

class foo {
var $string;

function add_some_extra($string) {
   $this->string .= $string . 'and something extra.';
}
}

$obj = new foo;
$obj->add_some_extra('This is a string, ');
echo $this->string; 

Yes, thats the way I use with classes but more like this way:

Code:

<?php

class foo {


function add_some_extra($string) {
   return .= $string . 'and something extra.';
}
}

$obj = new foo;
echo $obj->add_some_extra('This is a string, ');

but what is a real world example for passing by reference?

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but what is a real world example for passing by reference?

It is usefull when you want to keep arrays-collections of objects without using a lot of memory (with the clone command) or when you are using procedural programming.

In oop I don't think is needed frequently.

but what is a real world example for passing by reference?

It is usefull when you want to keep arrays-collections of objects without using a lot of memory (with the clone command) or when you are using procedural programming.

In oop I don't think is needed frequently.

strange, while reading the iterator article I found passing by reference inside classes like:

Code:

<?php
function & foo($val) {
  //code here
}

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I haven't seen that before, but maybe is the same thing with foo(&$val, &$val2, etc....)

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