function check_form(f)
    {
    	for(var i = 0; i < document[f].elements.length; i++)
    	{
    		if ((document[f].elements[i].type != "hidden" && document[f].elements[i].type != "checkbox") && (document[f].elements[i].value == ""))
    		{
    			alert("Please enter "+ document[f].elements[i].name);
    			document[f].elements[i].focus();
    			return false;
    		}
    	}
		m=check_email(document[f].email.value);
		if(m==false)
		{
			document[f].email.focus();
			return false;
		}
		//turing check
//		if(document[f].turing.value != document[f].code.value)
//		{
//			alert("Code incorrect");
//			document[f].code.focus();
//			return false;
//		}		
		return true;
    }
    
    function check_email(mailObj)
    {
     var decadr, decdomaine, nbparties, longdernpartie;
    
     if(mailObj.search(/ /) != -1)
      {alert("E-mail: no blanks allowed");
       return false;
      }
     decadr = mailObj.split('@');
     if(decadr.length != 2 || decadr[0] == "" || decadr[1] == "")
      {alert("E-mail: format must be login@domaine.xxx");
       return false;
      }
     decdomaine = decadr[1].split('.');
     nbparties=decdomaine.length;
     if(nbparties > 1)
     { longdernpartie=decdomaine[nbparties-1].length;
       if((longdernpartie != 2) && (longdernpartie != 3))
    	{ alert("E-mail: Incorrect domaine name, only 2 or 3 letters after the dot");
    	  return false;
    	}
     }
     else
     { alert("E-mail: Domaine name missing");
       return false;
     }
     return true;
    }