This extension is enabled by default, although it may be disabled by compiling with --without-iconv.
The optional --with-iconv-dir directive is used to specify the location of iconv on the system that PHP is being compiled on, otherwise only the default locations are scanned.
Note: Note to PHP 4 users
Enabling this extension requires building with --with-iconv=[DIR], or Windows users may enable by having iconv.dll available in the systems PATH, and php_iconv.dll enabled in php.ini.