Programming PHP

Example 5-3. Sorting arrays (continued)
Values :
Natural-Order Sorting
PHP’s built-in sort functions correctly sort strings and numbers, but they don’t correctly
sort strings that contain numbers. For example, if you have the filenames
ex10.php, ex5.php, and ex1.php, the normal sort functions will rearrange them in
this order: ex1.php, ex10.php, ex5.php. To correctly sort strings that contain numbers,
use the natsort( ) and natcasesort( ) functions:
$output = natsort(input);
$output = natcasesort(input);
Sorting Multiple Arrays at Once
The array_multisort( ) function sorts multiple indexed arrays at once:
array_multisort(array1 [, array2, ... ]);
Pass it a series of arrays and sorting orders (identified by the SORT_ASC or SORT_DESC
constants), and it reorders the elements of all the arrays, assigning new indexes. It is
similar to a join operation on a relational database.
Imagine that you have a lot of people, and several pieces of data on each person:
$names = array('Tom', 'Dick', 'Harriet', 'Brenda', 'Joe');
$ages = array(25, 35, 29, 35, 35);
$zips = array(80522, '02140', 90210, 64141, 80522);
The first element of each array represents a single record—all the information known
about Tom. Similarly, the second element constitutes another record—all the information
known about Dick. The array_multisort( ) function reorders the elements of
the arrays, preserving the records. That is, if Dick ends up first in the $names array
after the sort, the rest of Dick’s information will be first in the other arrays too. (Note
that we needed to quote Dick’s zip code to prevent it from being interpreted as an
octal constant.)
Here’s how to sort the records first ascending by age, then descending by zip code:
array_multisort($ages, SORT_ASC, $zips, SORT_DESC, $names, SORT_ASC);
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