学步园

看了好多关于STL multimap的使用方法，但就这个还是较简洁。现转过来，算是笔记吧：

<br /> #include <string.h><br /> #include <iostream><br /> #include <map><br /> #include <utility><br /> using namespace std;<br /> int main()<br /> {<br /> // Compare (<) function not required since it is built into string class.<br /> // else declaration would comparison function in multimap definition.<br /> // i.e. multimap<string, int, compare> m;<br /> multimap<string, int> m;<br /> m.insert(pair<string, int>("a", 1));<br /> m.insert(pair<string, int>("c", 2));<br /> m.insert(pair<string, int>("b", 3));<br /> m.insert(pair<string, int>("b", 4));<br /> m.insert(pair<string, int>("a", 5));<br /> m.insert(pair<string, int>("b", 6));<br /> cout << "Number of elements with key a: " << m.count("a") << endl;<br /> cout << "Number of elements with key b: " << m.count("b") << endl;<br /> cout << "Number of elements with key c: " << m.count("c") << endl;<br /> cout << "Elements in m: " << endl;<br /> for (multimap<string, int>::iterator it = m.begin();<br /> it != m.end();<br /> ++it)<br /> {<br /> cout << " [" << (*it).first << ", " << (*it).second << "]" << endl;<br /> }<br /> pair<multimap<string, int>::iterator, multimap<string, int>::iterator> ppp;<br /> // equal_range(b) returns pair<iterator,iterator> representing the range<br /> // of element with key b<br /> ppp = m.equal_range("b");<br /> // Loop through range of maps of key "b"<br /> cout << endl << "Range of /"b/" elements:" << endl;<br /> for (multimap<string, int>::iterator it2 = ppp.first;<br /> it2 != ppp.second;<br /> ++it2)<br /> {<br /> cout << " [" << (*it2).first << ", " << (*it2).second << "]" << endl;<br /> }<br /> // Can't do this (??)<br /> // cout << ppp.first << endl;<br /> // cout << ppp.second << endl;<br /> m.clear();<br /> }<br />  

结果：

Number of elements with key a: 2
Number of elements with key b: 3
Number of elements with key c: 1
Elements in m:
  [a, 1]
  [a, 5]
  [b, 3]
  [b, 4]
  [b, 6]
  [c, 2]

Range of "b" elements:
  [b, 3]
  [b, 4]
  [b, 6]

来源：http://www.yolinux.com/TUTORIALS/CppStlMultiMap.html