本文介绍了如何从 C++ 多图中删除特定对?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
#include <map>
...
multimap<char,int> mymap;
mymap.insert(pair<char,int>('a',10));
mymap.insert(pair<char,int>('b',15));
mymap.insert(pair<char,int>('b',20));
mymap.insert(pair<char,int>('c',25));
Say I now want to remove one of the pairs I have just added to the map.
I have examples to remove an entire key entry, which for key 'b' would remove both 'b',15 and 'b',20.
But what is the code to remove just, say, the pair 'b',20?
解决方案
You can use std::multimap<char, int>::equal_range, which will give you an iterator range containing all pairs which have a certain key. So if you look for 'b', you will get an iterator range containing all pairs which have 'b' as the key.
You can then simply iterate over the range, and erase any pair you see fit, by erasing the iterator.
multimap<char,int> mymap;
mymap.insert(pair<char,int>('a',10));
mymap.insert(pair<char,int>('b',15));
mymap.insert(pair<char,int>('b',20));
mymap.insert(pair<char,int>('c',25));
typedef multimap<char, int>::iterator iterator;
std::pair<iterator, iterator> iterpair = mymap.equal_range('b');
// Erase (b,15) pair
//
iterator it = iterpair.first;
for (; it != iterpair.second; ++it) {
if (it->second == 15) {
mymap.erase(it);
break;
}
}
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