(PHP 5 >= 5.2.0)
filter_input — Gets a specific external variable by name and optionally filters it
One of INPUT_GET, INPUT_POST, INPUT_COOKIE, INPUT_SERVER, or INPUT_ENV.
Name of a variable to get.
The ID of the filter to apply. The Types of filters manual page lists the available filters.
Associative array of options or bitwise disjunction of flags. If filter accepts options, flags can be provided in "flags" field of array.
Value of the requested variable on success, FALSE if the filter fails, or NULL if the variable_name variable is not set. If the flag FILTER_NULL_ON_FAILURE is used, it returns FALSE if the variable is not set and NULL if the filter fails.
Example #1 A filter_input() example 以上例程的输出类似于：
<?php
$search_html = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_SPECIAL_CHARS);
$search_url = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_ENCODED);
echo "You have searched for $search_html.
";
echo "<a href='?search=$search_url'>Search again.</a>";
?>
You have searched for Me & son.
<a href='?search=Me%20%26%20son'>Search again.</a>