PHP CookBook

Recipe 18.14 Reading Configuration Files

18.14.1 Problem

You want to use configuration files to initialize settings in your programs.

18.14.2 Solution

Use parse_ini_file( ):

$config = parse_ini_file('/etc/myapp.ini');

18.14.3 Discussion

The function parse_ini_file( ) reads configuration files structured like PHP's main php.ini file. Instead of applying the settings in the configuration file to PHP's configuration, however, parse_ini_file( ) returns the values from the file in an array.

For example, when parse_ini_file( ) is given a file with these contents:

; physical features
eyes=brown
hair=brown
glasses=yes

; other features
name=Susannah
likes=monkeys,ice cream,reading

The array it returns is:

Array
(
    [eyes] => brown
    [hair] => brown
    [glasses] => 1
    [name] => Susannah
    [likes] => monkeys,ice cream,reading
)

Blank lines and lines that begin with ; in the configuration file are ignored. Other lines with name=value pairs are put into an array with the name as the key and the value, appropriately, as the value. Words such as on and yes as values are returned as 1, and words such as off and no are returned as the empty string.

To parse sections from the configuration file, pass 1 as a second argument to parse_ini_file( ). Sections are set off by words in square brackets in the file:

[physical]
eyes=brown
hair=brown
glasses=yes

[other]
name=Susannah
likes=monkeys,ice cream,reading

If this file is in /etc/myapp.ini, then:

$conf = parse_ini_file('/etc/myapp.ini',1);

Puts this array in $conf:

Array
(
    [physical] => Array
        (
            [eyes] => brown
            [hair] => brown
            [glasses] => 1
        )

    [other] => Array
        (
            [name] => Susannah
            [likes] => monkeys,ice cream,reading
        )

)

Your configuration file can also be a valid PHP file that you load with require instead of parse_ini_file( ). If the file config.php contains:

<?php

// physical features
$eyes = 'brown';
$hair = 'brown';
$glasses = 'yes';

// other features
$name = 'Susannah';
$likes = array('monkeys','ice cream','reading');
?>

You can set the variables $eyes, $hair, $glasses, $name, and $likes with:

require 'config.php';

The configuration file loaded by require needs to be valid PHP — including the <?php start tag and the ?> end tag. The variables named in config.php are set explicitly, not inside an array, as in parse_ini_file( ). For simple configuration files, this technique may not be worth the extra attention to syntax, but it is useful for embedding logic in the configuration file:

<?php

$time_of_day = (date('a') == 'am') ? 'early' : 'late';

?>

The ability to embed logic in configuration files is a good reason to make the files PHP code, but it is helpful also to have all the variables set in the configuration file inside an array. Upcoming versions of PHP will have a feature called namespaces, which is the ability to group variables hierarchically in different bunches; you can have a variable called $hair in two different namespaces with two different values. With namespaces, all the values in a configuration file can be loaded into the Config namespace so they don't interfere with other variables.

18.14.4 See Also

Documentation on parse_ini_file( ) at http://www.php.net/parse-ini-file; information about namespaces and other upcoming PHP language features is available at http://www.php.net/ZEND_CHANGES.txt.