Filter-Funktionen

Inhaltsverzeichnis

filter_has_var — Prüft, ob eine Variable des angegebenen Typs existiert
filter_id — Liefert die Filter-ID zu einem Filternamen
filter_input — Nimmt eine Variable von Außen entgegen und filtert sie optional
filter_input_array — Nimmt mehrere Variablen von Außen entgegen und filtert sie optional
filter_list — Liefert eine Liste aller unterstützten Filter
filter_var — Filtert eine Variable mit einem angegebenen Filter
filter_var_array — Nimmt mehrere Variablen entgegen und filtert sie optional

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User Contributed Notes 2 notes

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vojtech at x dot cz ¶

18 years ago

Also notice that filter functions are using only the original variable values passed to the script even if you change the value in super global variable ($_GET, $_POST, ...) later in the script.

<?php
echo filter_input(INPUT_GET, 'var'); // print 'something'
echo $_GET['var']; // print 'something'
$_GET['var'] = 'changed';
echo filter_input(INPUT_GET, 'var'); // print 'something'
echo $_GET['var']; // print 'changed'
?>

In fact, external data are duplicated in SAPI before the script is processed and filter functions don't use super globals anymore (as explained in Filter tutorial bellow, section 'How does it work?').

down

fumble1 at web dot de ¶

17 years ago

I recommend you to use the FILTER_REQUIRE_SCALAR (or FILTER_REQUIRE_ARRAY) flags, since you can use array-brackets both to access string offsets and array-element -- however, not only this can lead to unexpected behaviour. Look at this example:

<?php
$image = basename(filter_input(INPUT_GET, 'src', FILTER_UNSAFE_RAW, FILTER_FLAG_STRIP_LOW));
// further checks
?>

/script.php?src[0]=foobar will cause a warning. :-(
Hence my recommendation:

<?php
$image = basename(filter_input(INPUT_GET, 'src', FILTER_UNSAFE_RAW, FILTER_REQUIRE_SCALAR | FILTER_FLAG_STRIP_LOW));
// further checks
?>

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