Description:
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The manual page for ctype_alnum() - http://www.php.net/manual/en/function.ctype-alnum.php - states that "the function is equivalent to preg_match('/^[a-z0-9]+$/i', $text).". However $ matches a trailing newline as well as the end of the subject; it should be replaced with \z which only matches the end of the subject.

Reproduce code:
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$s = "abc\n";
var_dump(ctype_alnum($s), preg_match("/^[a-z0-9]+$/i", $s));

Expected result:
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bool(false)
int(0)

Actual result:
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bool(false)
int(1)