# Zend_Config_Ini

`Zend_Config_Ini` enables developers to store configuration data in a familiar INI format and read them in the application by using nested object property syntax. The INI format is specialized to provide both the ability to have a hierarchy of configuration data keys and inheritance between configuration data sections. Configuration data hierarchies are supported by separating the keys with the dot or period character ("."). A section may extend or inherit from another section by following the section name with a colon character (":) and the name of the section from which data are to be inherited.

## Parsing the INI File

`Zend_Config_Ini` utilizes the `parse_ini_file()` PHP function. Please review this documentation to be aware of its specific behaviors, which propagate to `Zend_Config_Ini`, such as how the special values of "`TRUE`", "`FALSE`", "yes", "no", and "`NULL`" are handled.

## Key Separator

By default, the key separator character is the period character ("."). This can be changed, however, by changing the `$options` key nestSeparator when constructing the `Zend_Config_Ini` object. For example:

    $options['nestSeparator'] = ':';
    $config = new Zend_Config_Ini('/path/to/config.ini',
                                  'staging',
                                  $options);

## Using Zend_Config_Ini

This example illustrates a basic use of `Zend_Config_Ini` for loading configuration data from an INI file. In this example there are configuration data for both a production system and for a staging system. Because the staging system configuration data are very similar to those for production, the staging section inherits from the production section. In this case, the decision is arbitrary and could have been written conversely, with the production section inheriting from the staging section, though this may not be the case for more complex situations. Suppose, then, that the following configuration data are contained in `/path/to/config.ini`:

    ; Production site configuration data
    [production]
    webhost                  = www.example.com
    database.adapter         = pdo_mysql
    database.params.host     = db.example.com
    database.params.username = dbuser
    database.params.password = secret
    database.params.dbname   = dbname

    ; Staging site configuration data inherits from production and
    ; overrides values as necessary
    [staging : production]
    database.params.host     = dev.example.com
    database.params.username = devuser
    database.params.password = devsecret

Next, assume that the application developer needs the staging configuration data from the INI file. It is a simple matter to load these data by specifying the INI file and the staging section:

    $config = new Zend_Config_Ini('/path/to/config.ini', 'staging');

    echo $config->database->params->host;   // prints "dev.example.com"
    echo $config->database->params->dbname; // prints "dbname"

## Zend_Config_Ini Constructor Parameters

Parameter | Notes
--- | ---
`$filename` | The INI file to load.
`$section` | The [section] within the ini file that is to be loaded. Setting this parameter to `NULL` will load all sections. Alternatively, an array of section names may be supplied to load multiple sections.

`$options` (default `FALSE`)

Options array. The following keys are supported:

- allowModifications: Set to `TRUE` to allow subsequent modification of loaded configuration data in-memory. Defaults to `NULL`

- nestSeparator: Set to the character to be used as the nest separator. Defaults to "."