undefined variable has a value

Bug #22367

Submitted:

2003-02-21 17:31 UTC

Modified:

2003-08-26 23:24 UTC

Votes:	4
Avg. Score:	5.0 ± 0.0
Reproduced:	4 of 4 (100.0%)
Same Version:	4 (100.0%)
Same OS:	3 (75.0%)

From:

stanislav dot chachkov at epfl dot ch

Assigned:

Status:

Closed

Package:

Scripting Engine problem

PHP Version:

4.3.0

OS:

Solaris8

Private report:

CVE-ID:

None

[2003-02-21 17:31 UTC] stanislav dot chachkov at epfl dot ch

In a method we have that ($a is undefined,
but this also works if you substitute $a by any other name):

function getColumnValue($col_name){
  var_dump($a); echo "a=$a  <br>";
  ...
}


This method is called a number of times and the output is like this:

NULL a=
NULL a=
...
NULL a=Etape_Editor_IDEtape_Editor_ID''

Actually "EtapeEditor_ID" was the parameter of PREVIOUS call to one of methods of this class. 
 
I can not reproduce this problem with a short script, it seems that it appears only when the number of classes, objects and calls is large, otherwise it works fine.

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[2003-02-23 13:16 UTC] stanislav dot chachkov at epfl dot ch

This is the test case:

<?
class A{
  var $fields;
  
  function getID(){
    return $this->getColumnValue($this->getPK());
  }
  
  function getColumnValue($col_name){
    return $this->fields[$col_name];
  }
  
 
  function save(){
    $this->getID();
    $i=333;
    echo "Dump of z: ";
    var_dump($z);
    echo "<br>z=";
    echo $z;
    echo "<br>";
    if($boo){
      echo "undefined is now defined<br>";
    }else{
      echo "undefined is undefined<br>";
    }
    
    $s1="YES";
    $s2="NO";
    
    echo "s1=$s1, s2=$s2";
  }
}


class B extends A{
  function getPK(){
    return "ID";
  }
  
  function &getColumnValue($col_name){
    return parent::getColumnValue($col_name);
  }
}


$b=new B();
if(!$b->getID()){}
$b->save();

?>

The output that we have is:

Dump of z: NULL
z=333
undefined is now defined
s1=NO, s2=NO

[2003-02-24 15:11 UTC] stanislav dot chachkov at epfl dot ch

We found a workaround: getColumnValue functions should both return a reference or both return a value. 
Actually it is also possible to return a reference from class A and value from sub class B, but the inverse breaks the stack.

[2003-08-26 23:24 UTC] sniper@php.net

This is fixed in PHP 5, won't be fixed in PHP 4.