java用迭代器只能往后迭代
但是C++可以往后迭代和往前迭代
 

1、C++Map往后迭代

map<int,int> amap;  
amap.insert(pair<int,int>(1,1));  
amap.insert(pair<int.int>(2,2));  
map<int,int>::iterator it;  
for(it = amap.begin();it != ampa.end();it++)//从前向后  
{  cout<<"key:"<<it->first<<" value:"<<it->second<<endl;	
}

2、C++Map往前迭代

map<int,int>::reverse_iterator rit;  
for(rit = amap.rbegin();rit != amap.rend();rit++)//从后向前  
{  cout<<"key:"<<rit->first<<" value:"<<rit->second<<endl;  
}