function onError($errCode, $errMesg, $errFile, $errLine) {        
    echo "Error Occurred\n";        
    throw new Exception($errMesg);    
  }     
  function onException($e) {        
    echo $e->getMessage();    
  }     
  set_error_handler("onError");     
  set_exception_handler("onException"); 
  try {
    $mm=0/0;
    echo $mm;
  } catch (Exception $e) {
    echo $e->getCode()."\n";
    echo $e->getMessage()."\n";
  }

--------------------------------

一定要定义和调用

set_error_handler("onError");

set_exception_handler("onException");

否则 进不去catch（）{}里面去的