PHP Functions

PHP comes standard with many functions and constructs. There are also functions that require specific PHP extensions compiled in otherwise you’ll get fatal “undefined function” errors. For example, to use image functions such as imagecreatetruecolor(), you’ll need your PHP compiled with GD™ support. Or, to use mysql_connect() you’ll need your PHP compiled in with MySQL support. There are many core functions that are included in every version of PHP like the string and variable functions. A call to phpinfo() or get_loaded_extensions() will show you which extensions are loaded into your PHP. Also note that many extensions are enabled by default and that the PHP manual is split up by extension. See the configuration, installation, and individual extension chapters, for information on how to setup your PHP.