迭代器遍历 and auto遍历

1. 迭代器

   map<string,int>::iterator it;
   for(it=mp.begin();it!=mp.end();it++)
   {
   cout<<it->first<<" "<<it->second<<endl;
   }

2. auto

   for(auto l:mp)
   {
   cout<<l.first<<" "<<l.second<<endl;
   }