Edit report at http://bugs.php.net/bug.php?id=53971&edit=1
ID: 53971 Updated by: dtajchre...@php.net Reported by: david at frankieandshadow dot com Summary: isset() and empty() produce apparently spurious runtime error -Status: Open +Status: Bogus Type: Bug Package: Arrays related Operating System: Linux, Redhat Enterprise PHP Version: 5.3.5 Block user comment: N Private report: N New Comment: $obj->m is an empty string. You try to access a non-integer offset. Non-integer offsets are converted to integers. So in other words: $obj->m['a'] becomes $obj->m[0] $obj->m is an empty string and $obj->m[0] doesn't exist This behavior is documented here: http://us.php.net/manual/en/language.types.string.php "Warning Writing to an out of range offset pads the string with spaces. Non-integer types are converted to integer. Illegal offset type emits E_NOTICE. Negative offset emits E_NOTICE in write but reads empty string. Only the first character of an assigned string is used. Assigning empty string assigns NUL byte." Simplifying the problem: http://codepad.org/G31wr4oJ Previous Comments: ------------------------------------------------------------------------ [2011-02-09 13:12:44] david at frankieandshadow dot com Description: ------------ First, apologies, this is 5.3.3. I have no means of upgrading to check whether this is a fixed issue. I can't see anything similar in the bug database. An expression of the form isset($obj->m['a']['b']) produces a runtime error when m is not actually an array but a zero length string: Uninitialized string offset: 0 The same is the case if I use empty instead of isset. The same code worked in 5.2. Changing it to isset($obj->m['a']) && isset($obj->m['a']['b']) works. isset is not supposed to produce any runtime error, surely, in this kind of use. The object member values arise from a database lookup, and normally the field (m above) will be a serialized array in the database, but the first time the database column will be empty, leading to an empty string assignment to m. In addition once populated the object is stored in $_SESSION (actually in $_SESSION['p']['q']) and then $obj is obtained by assignment from the session, like this $session =& $_SESSION['p']; // where $_SESSION['p'] is set in a previous page // populate new $obj1 from database $session['q'] = $obj1; ... $obj =& $session['q']; and the offending code is then executed elsewhere some time later. However, abstracting the code from this much bigger program does not demonstrate the problem, which suggests to me something is corrupted somewhere. This is what I tried on its own, which is as close as I can reasonably get to the situation here, but it works. (The =& are leftovers from what was originally a PHP4 app; I know all objects are assigned by reference in PHP5). class c { var $m; } session_start(); if (! isset($_SESSION['p'])) { $_SESSION['p'] = array(); echo "set session array"; exit; } $session =& $_SESSION['p']; $obj1 = new c(); $obj1->m = ''; $session['q'] = $obj1; $obj =& $session['q']; function check() { global $obj; echo (isset($obj->m['a']['b']) ? 'Yes' : 'No'); } check(); Expected result: ---------------- isset to return FALSE Actual result: -------------- runtime error Uninitialized string offset: 0 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=53971&edit=1