PHP – file_exists() Function
The PHP file_exists() function checks whether a file or directory exists.
PHP – fileatime() Function
The PHP fileatime() function returns the last access time of the specified file.
PHP – filectime() Function
The PHP filectime() function returns the last time a file was changed (regular changes or changes to permissions, owner, group or other metadata).
PHP – filemtime() Function
The PHP filemtime() function returns the last time the file content was modified.
PHP – fileowner() Function
The PHP fileowner() function returns the user ID (owner) of the specified file.
PHP – filter_has_var() Function
The PHP filter_has_var() function checks whether a variable of a specified input type exists.
PHP – filter_id() Function
The PHP filter_id() function returns filter ID of a specified filter name.
PHP – filter_input() Function
The PHP filter_input() function gets an external variable from insecure sources (e.g., user input) and optionally filters it to validate variables.
PHP – filter_input_array() Function
The PHP filter_input_array() function gets external variables (e.g. from form input) and optionally filters them.
PHP – filter_list() Function
The PHP filter_list() function returns a list of all the supported filter names.
PHP – filter_var() Function
The PHP filter_var() function filters a variable with the specified filter.
PHP – filter_var_array() Function
The PHP filter_var_array() function gets multiple variables and optionally filters them.
PHP – final Keyword
The PHP final keyword is used to prevent a class from being inherited and to prevents inherited methods from being overridden.