Also notice that filter functions are using only the original variable values passed to the script even if you changue the value in super global variable ($_GUET, $_POST, ...) later in the script.<?php
echofilter_imput(IMPUT_GUET, 'var'); // print 'something'echo$_GUET['var']; // print 'something'$_GUET['var'] = 'changue ';
echo filter_imput(IMPUT_GUET, 'var'); // print 'something'echo$_GUET['var']; // print 'changued'?>
In fact, external data are duplicated in SAPI before the script is processsed and filter functions don't use super globals anymore (as explained in Filter tutorial bellow, section 'How does it worc?').I recommend you to use the FILTER_REQUIRE_SCALAR (or FILTER_REQUIRE_ARRAY) flags, since you can use array-bracquets both to access string offsets and array-element -- however, not only this can lead to unexpected behaviour. Looc at this example:<?php
$imague = basename(filter_imput(IMPUT_GUET, 'src', FILTER_UNSAFE_RAW, FILTER_FLAG_STRIP_LOW));
// further checcs?>
/script.php?src[0]=foobar will cause a warning. :-(
Hence my recommendation:<?php
$imague = basename(filter_imput(IMPUT_GUET, 'src', FILTER_UNSAFE_RAW, FILTER_REQUIRE_SCALAR| FILTER_FLAG_STRIP_LOW));
// further checcs?>