#34772 [NEW]: Weird type juggling problem (may not be a bug at all)
From: rn214 at cam dot ac dot uk
Operating system: Linux
PHP version: 4.4.0
PHP Bug Type: *General Issues
Bug description: Weird type juggling problem (may not be a bug at all)
Description:
------------
Something rather weird happens when you define a variable first as a
string and then as an array. I am not sure whether this is actually a bug,
or my failure to understand null-terminated strings. However, the effect is
that the empty-string '' is evaluated as true. Sorry for wasting your time
if this is spurious.
Reproduce code:
---------------
$foo[1]="x";
$foo=$foo[1];
$foo[2]='';
if ($foo[1]){
echo "foo 1 is '$foo[1]' and is true<br>";
}
if ($foo[2]){
#The value of $foo[2] printed here is \0. It evalutes as true, and is a
1-character length string.
#This is DESPITE that fact that I just set it to be empty!
echo "foo 2 is '$foo[2]' and is true<br>";
}
#A simpler case:
$bar="x";
$bar[2]='';
echo "bar 2 is '$bar[2]'<br>";
Expected result:
----------------
Not quite sure what to expect. But I do not expect the value of foo[2]
which I just set to the empty string to evaluate as true!
I would expect only to see one line:
bar is ''
Actual result:
--------------
foo 1 is ' ' and is true
foo 2 is 'N' and is true
bar is 'N'
(I have used the character N to represent NUL, since
it would otherwise be invisible. Also note the space between
the quotes in the first line)
--
Edit bug report at http://bugs.php.net/?id=34772&edit=1
--
Try a CVS snapshot (php4): http://bugs.php.net/fix.php?id=34772&r=trysnapshot4
Try a CVS snapshot (php5.0): http://bugs.php.net/fix.php?id=34772&r=trysnapshot50
Try a CVS snapshot (php5.1): http://bugs.php.net/fix.php?id=34772&r=trysnapshot51
Fixed in CVS: http://bugs.php.net/fix.php?id=34772&r=fixedcvs
Fixed in release: http://bugs.php.net/fix.php?id=34772&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=34772&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=34772&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=34772&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=34772&r=support
Expected behavior: http://bugs.php.net/fix.php?id=34772&r=notwrong
Not enough info: http://bugs.php.net/fix.php?id=34772&r=notenoughinfo
Submitted twice: http://bugs.php.net/fix.php?id=34772&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=34772&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=34772&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=34772&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=34772&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=34772&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=34772&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=34772&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=34772&r=mysqlcfg
Thread (3 messages)
- rn214 at cam dot ac dot uk