Entry

Getting "Warning: Undefined variable: foo in D:\path\dir\file.php on line n" for all unposted variables. This error occurs even for if($foo) {

Feb 3rd, 2001 01:17
Philip Olson, Mike Boucher,

This has to do with error reporting, read about this a bit here :

    http://www.php.net/manual/en/function.error-reporting.php 

And for a definition of types : 

    http://www.php.net/manual/en/phpdevel-errors.php

You may have E_ALL or E_NOTICE on within php.ini  BTW, consider doing 
this instead :

    if (empty($submit))  {

    - or -
    
    if (!empty($submit)) {
    
As using empty (or isset) for this task will not result in such errors.

    http://www.php.net/manual/en/function.empty.php

    http://www.php.net/manual/en/function.isset.php

As well as string comarison functions, such as :

    http://www.php.net/manual/en/function.strcmp.php

Essentially, when error reporting is turned up high enough, errors will 
result from undefined variables.  For example, this will also result 
with an error rather then return true :

    if ($var == '') {

As stated above, using empty or isset is preferred for this task.