Before php 5.2.0 when we have to validate or filter user data, we normally use regex and some php functions. Some of those regex are difficult to understand. So normally most of the coders search in google to collect the correct regex to validate data and also use some php functions to filter data.

In php 5.2.0 a new extension is provided named filter to make these filter tasks much easy.  You can install it in your linux distro by simply typing in shell  pecl install filter

Before proceeding next at first check the available filters in your system:

    echo '<pre>';
    print_r(filter_list());
    echo '</pre>';

Output in my system:

Array
(
    [0] => int
    [1] => boolean
    [2] => float
    [3] => validate_regexp
    [4] => validate_url
    [5] => validate_email
    [6] => validate_ip
    [7] => string
    [8] => stripped
    [9] => encoded
    [10] => special_chars
    [11] => unsafe_raw
    [12] => email
    [13] => url
    [14] => number_int
    [15] => number_float
    [16] => magic_quotes
    [17] => callback
)

filter_list() is a method that returns a list of all supported filters.

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