Returning Lists from Functions

Returning arrays from functions is one way to return multiple values from a single function call, but there's anotheryou can return a list. This is a handy way of returning multiple values from a single function call. We can use the same function, array_doubler, as in the previous chunk:

 function array_doubler($arr) {     for($loop_index = 0; $loop_index < count($arr); $loop_index++){         $arr[$loop_index] *= 2;     }     return $arr; }

This function is passed an array. It doubles each element's value in the array and returns that array. When that array is returned, you can assign it to a list of variables like this:

 list($first, $second, $third, $fourth, $fifth, $sixth) = array_doubler($array);

This assigns the first element of the array to $first, the second element to $second, and so on. All that's left is to echo the values of $first, $second, and so on, as you see in phplist.php, Example 4-7.

Example 4-7. Returning lists from functions, phplist.php

 <HTML>         <HEAD>             <TITLE>                 Return lists from functions             </TITLE>         </HEAD>         <BODY>             <H1>                 Return lists from functions             </H1>             <?php                 $array = array(1, 2, 3, 4, 5, 6);                 list($first, $second, $third, $fourth, $fifth, $sixth) =                     array_doubler($array);                 echo "\$first: $first<BR>";                 echo "\$second: $second<BR>";                 echo "\$third: $third<BR>";                 echo "\$fourth: $fourth<BR>";                 echo "\$fifth: $fifth<BR>";                 echo "\$sixth: $sixth<BR>";                 function array_doubler($arr)                 {                     for($loop_index = 0; $loop_index < count($arr);                         $loop_index++){                         $arr[$loop_index] *= 2;                     }                     return $arr;                 }             ?>     </BODY> </HTML>

The results appear in Figure 4-7, where, as you see, we've been able to assign the various array elements to the variables $first, $second, $third, and so on.

Figure 4-7. Returning lists from functions.

What if you only wanted, say, the first three elements of the returned array? You could do something like this, ignoring the last three elements:

 list($first, $second, $third) = array_doubler($array); echo "\$first: $first\n"; echo "\$second: $second\n"; echo "\$third: $third\n";

No problem at all. Note, however, that you can't directly return a list from a function like this:

 return list($arr[0], $arr[1], $arr[2], $arr[3], $arr[4], $arr[5]);  //Won't work!