[SOLVED] References??

[kirk112]

I am trying to get my head around references and why you would use them,

 

for example if the $_get['page'] is not passed to the page I get 'Notice: Undefined index: per_page in ' but if I put the & before I get no error messages, is this one of the usages of refeneces?

 

$array = array(

'per_page'              => &$_GET['per_page'],

'per_page_extra'      => $_GET['per_page'])

 

Sorry for the simple question

 

thanks for your help

[MadTechie]

erm.. no

 

thats what isset() is for

 

ie

if( isset($_GET['page']) )
{
echo $_GET['page'];
}

 

as for referances

instead of passing a value to a function and then having to return it you can use a referance

ie

Note: the foo function is NOT returning anything, but $a still increases by 1

<?php
function foo(&$var)
{
    $var++;
}

$a=5;
echo $a."<br>";
foo($a);
echo $a."<br>";
?> 

 

 

What References Are

 

References in PHP are a means to access the same variable content by different names. They are not like C pointers; instead, they are symbol table aliases. Note that in PHP, variable name and variable content are different, so the same content can have different names. The most close analogy is with Unix filenames and files - variable names are directory entries, while variable contents is the file itself. References can be thought of as hardlinking in Unix filesystem.

 

SO.. to sum up

 

$b=100;
$a = $b;//$a equals 100
$c = & $b; //$c equals $b (not 100 but whatever $b is)

$b=$b+100;
echo "a=$a, b=$b, c=$c";

 

 

Hope that helps

[kirk112]

Arrr I now understand.

 

I knew about isset but was trying to be lazy have about 50 values and did not want to do if isset() for each of them

 

Thanks for the post!!