C++之try...catch...

以下语句引用HappyTree（笨笨·天行健）在某个问题中的回复。

贴一段来自BS的TCPL话：  
  When   a   program   is   composed   of   separate   modules,   and   especially   when   those   modules   come   from   separately   developed   libraries,   error   handling   needs   to   be   separated   into   two   distinct   parts:  
  [1]   The   reporting   of   error   conditions   that   cannot   be   resolved   locally  
  [2]   The   handling   of   errors   detected   elsewhere  
  The   author   of   a   library   can   detect   run-time   errors   but   does   not   in   general   have   any   idea   what   to   do   about   them.   The   user   of   a   library   may   know   how   to   cope   with   such   errors   but   cannot   detect   them   －or   else   they   would   be   handled   in   the   user's   code   and   not   left   for   the   library   to   find.  
  我想这段话还是比较清楚的。当你写一个库时，比如strcpy，你能检测到运行时错误的存在，但你不知道该如何来做一个通用的处理，这时你就可以抛出一个异常，让调用strcpy的用户来处理。  
  如果你知道如何去处理所有运行时错误，if...else...足够了。