PHP Filter Introduction
This PHP filters is used to validate and filter data coming from insecure sources, like user input.
Installation
The filter functions are part of the PHP core. There is no installation needed to use these functions.
PHP Filter Functions
PHP: indicates the earliest version of PHP that supports the function.
| Function | Description | PHP |
| filter_has_var() | Checks if a variable of a specified input type exist | 5 |
| filter_id() | Returns the ID number of a specified filter | 5 |
| filter_input() | Get input from outside the script and filter it | 5 |
| filter_input_array() | Get multiple inputs from outside the script and filters them | 5 |
| filter_list() | Returns an array of all supported filters | 5 |
| filter_var_array() | Get multiple variables and filter them | 5 |
| filter_var() | Get a variable and filter it | 5 |
PHP Filters
| ID Name | Description |
| FILTER_CALLBACK | Call a user-defined function to filter data |
| FILTER_SANITIZE_STRING | Strip tags, optionally strip or encode special characters |
| FILTER_SANITIZE_STRIPPED | Alias of “string” filter |
| FILTER_SANITIZE_ENCODED | URL-encode string, optionally strip or encode special characters |
| FILTER_SANITIZE_SPECIAL_CHARS | HTML-escape ‘”<>& and characters with ASCII value less than 32 |
| FILTER_SANITIZE_EMAIL | Remove all characters, except letters, digits and !#$%&’*+-/=?^_`{|}~@.[] |
| FILTER_SANITIZE_URL | Remove all characters, except letters, digits and $-_.+!*'(),{}|\\^~[]`<>#%”;/?:@&= |
| FILTER_SANITIZE_NUMBER_INT | Remove all characters, except digits and +- |
| FILTER_SANITIZE_NUMBER_FLOAT | Remove all characters, except digits, +- and optionally .,eE |
| FILTER_SANITIZE_MAGIC_QUOTES | Apply addslashes() |
| FILTER_UNSAFE_RAW | Do nothing, optionally strip or encode special characters |
| FILTER_VALIDATE_INT | Validate value as integer, optionally from the specified range |
| FILTER_VALIDATE_BOOLEAN | Return TRUE for “1”, “true”, “on” and “yes”, FALSE for “0”, “false”, “off”, “no”, and “”, NULL otherwise |
| FILTER_VALIDATE_FLOAT | Validate value as float |
| FILTER_VALIDATE_REGEXP | Validate value against regexp, a Perl-compatible regular expression |
| FILTER_VALIDATE_URL | Validate value as URL, optionally with required components |
| FILTER_VALIDATE_EMAIL | Validate value as e-mail |
| FILTER_VALIDATE_IP | Validate value as IP address, optionally only IPv4 or IPv6 or not from private or reserved rang |