PHP Filter Functions
PHP has built in filter functions which is used to filters data by either validating or sanitizing it. These filter functions are part of core PHP so you can use wherever required. Find below list of PHP - PHP filter functions:
| Function | Description |
|---|---|
| filter_has_var() | Checks if variable of specified type exists |
| filter_id() | Returns the ID number of a specified filter |
| filter_input() | Gets a specific external variable by name and optionally filters it |
| filter_input_array() | Gets multiple external variables and optionally filters them |
| filter_list() | Returns an array of all supported filters |
| filter_var_array() | Gets multiple variables and optionally filters them |
| filter_var() | Filters a variable with a specified filter |
Sanitize Filters in PHP
In PHP, sanitize filters are used to clean the user inputs.
| ID | Description |
|---|---|
| FILTER_SANITIZE_EMAIL | Remove all characters except letters, digits and !#$%&'*+-/=?^_`{|}~@.[] |
| FILTER_SANITIZE_ENCODED | URL-encode string, optionally strip or encode special characters. |
| FILTER_SANITIZE_MAGIC_QUOTES | Apply addslashes(). |
| FILTER_SANITIZE_NUMBER_FLOAT | Remove all characters except digits, +- and optionally .,eE |
| FILTER_SANITIZE_NUMBER_INT | Remove all characters except digits, plus (+) and minus (-) sign. |
| FILTER_SANITIZE_SPECIAL_CHARS | HTML-escape \'"<>& and characters with ASCII value less than 32, optionally strip or encode other special characters. |
| FILTER_SANITIZE_STRING | Strip tags, optionally strip or encode special characters. |
| FILTER_SANITIZE_STRIPPED | Alias of "string" filter. |
| FILTER_SANITIZE_URL | Remove all characters except letters, digits and $-_.+!*'(),{}|\^~[]`<>#%";/?:@&= |
| FILTER_UNSAFE_RAW | Do nothing, optionally strip or encode special characters. |
Validate Filters in PHP
In PHP, validation filters are used to validate the user inputs.
| ID | Description |
|---|---|
| FILTER_VALIDATE_BOOLEAN | Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise. |
| FILTER_VALIDATE_EMAIL | Validates value as e-mail. |
| FILTER_VALIDATE_FLOAT | Validates value as float. |
| FILTER_VALIDATE_INT | Validates value as integer optionally from the specified range. |
| FILTER_VALIDATE_IP | Validates value as IP address, optionally only IPv4 or IPv6 or not from private or reserved ranges. |
| FILTER_VALIDATE_REGEXP | Validates value against regexp, a Perl-compatible regular expression. |
| FILTER_VALIDATE_URL | Validates value as URL, optionally with required components. |
