HTTP_POST_VARS is not recognised

Hi, I am trying to write some simple application php3 but when I trying to extract values from the form using the following statement :-- while(list($name,$value)=each($HTTP_POST_VARS)): ---- ----- I get the following error:-- Warning: Variable passed to each() is not an array or object. The only reason which I can think of is that the HTTP_POST_VARS is not defined. But the installation states that the if the the php3 module gets embedded in the apache module, then all the php variables are created. Since HTTP_POST_VARS is a php variable it must also be defined. Can anybody clarify my doubt. Thanks in advance. Manas