php在函数外声明global变量有什么用？
我看wordpress的wp-settings.php文件中有这么一段：
/*
* These can't be directly globalized in version.php. When updating,
* we're including version.php from another install and don't want
* these values to be overridden if already set.
*/
global $wp_version, $wp_db_version, $tinymce_version, $required_php_version, $required_mysql_version;
require( ABSPATH . WPINC . '/version.php' );
不懂，求解释，谢谢啦 ^_^没有作用
并且在 wp-settings.php 中也没有看到
global $wp_version, $wp_db_version, $tinymce_version, $required_php_version, $required_mysql_version;
只有
require( ABSPATH . WPINC . '/version.php' );没作用
