function pruefen(f) {
   var fehler = "";  
   var radiocheck = "";   
   var i;  
   for (var j=0; j<f.elements.length; j++) {
      i = f.elements[j];
      if (i.id.indexOf("p_") !=0) {
      continue;
      }
      
      if (i.type=="text" || i.type=="password" || i.type=="textarea") {
         if (i.value == "") {
            fehler += i.name + "\n";
         }
      }
     
      if (i.type=="radio") {
         if (radiocheck.indexOf(i.name+ " ") < 0) {
            radiocheck += i.name + " ";
            eval("var radiogroup = f." + i.name);
            var ok = false;
            for (var k=0; k<radiogroup.length; k++) {
               if (radiogroup[k].checked) {
                  ok = true;
               }
            }
            if (!ok) {
               fehler += i.name + "\n";
            }
         }
      }

      
      if (i.type=="select-one" || i.type=="select-multiple") {
         if (i.selectedIndex == 0) {
            fehler += i.name + "\n";
         }
      }

     
      if (i.type=="checkbox") {
         if (i.checked == false) {
            fehler += i.name + "\n";
         }
      }
   }
   
   if (fehler != "") {
      alert("Bitte füllen Sie folgende Felder aus:\n" + fehler);
      return false;
   }
   return true;
}