当前位置：文江博客话题详情

如何检查我的迭代器是否没有任何东西

发布于 2024-09-17 21:21:43 字数 95 浏览 7 评论 0原文

我正在使用 multimap stl，我迭代我的地图，但在地图内没有找到我想要的对象，现在我想检查我的迭代器是否包含我想要的东西，但我遇到了困难，因为它不为空或其他东西。谢谢！

原文

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

人心善变 2024-09-24 21:21:43

如果它没有找到您想要的东西，那么它应该等于容器的 end() 方法返回的迭代器。

所以：

iterator it = container.find(something);
if (it == container.end())
{
  //not found
  return;
}
//else found

If it doesn't find the thing you want then it should equal the iterator returned by the end() method of the container.

So:

iterator it = container.find(something);
if (it == container.end())
{
  //not found
  return;
}
//else found

回复收藏 0 原文

也只是曾经 2024-09-24 21:21:43

为什么你要迭代你的地图来寻找某些东西，你应该像 ChrisW 一样在你的地图中找到一个键......

嗯，你是想在你的地图中找到值而不是键吗？那么你应该这样做：

map<int, string> myMap;
myMap[1] = "one"; myMap[2] = "two"; // etc.

// Now let's search for the "two" value
map<int, string>::iterator it;
for( it = myMap.begin(); it != myMap.end(); ++ it ) {
   if ( it->second == "two" ) {
      // we found it, it's over!!! (you could also deal with the founded value here)
      break; 
   }
}
// now we test if we found it
if ( it != myMap.end() ) {
   // you also could put some code to deal with the value you founded here,
   // the value is in "it->second" and the key is in "it->first"
}

Why are you iterating over your map to find something, you should go like ChrisW to find a key in your map...

Mmm, are you trying to find the value in your map and not the key? Then you should do:

map<int, string> myMap;
myMap[1] = "one"; myMap[2] = "two"; // etc.

// Now let's search for the "two" value
map<int, string>::iterator it;
for( it = myMap.begin(); it != myMap.end(); ++ it ) {
   if ( it->second == "two" ) {
      // we found it, it's over!!! (you could also deal with the founded value here)
      break; 
   }
}
// now we test if we found it
if ( it != myMap.end() ) {
   // you also could put some code to deal with the value you founded here,
   // the value is in "it->second" and the key is in "it->first"
}

回复收藏 0 原文

~没有更多了~