stuff about set multiset map multimap

　　A lot of interviewers like to ask the candidates the difference between set and multiset(map and multimap).What does multi actually mean?Multi-container could have duplicate element.Check the code below.

  1 /*********************************************
  2 Author:Zhou You
  3 Time:2014.09.06
  4 Feature:comparison of containers such as set,multiset,map and multimap.
  5 *********************************************/
  6 
  7 #include <iostream>
  8 #include <string>
  9 #include <map>
 10 #include <set>
 11 
 12 using namespace std;
 13 
 14 class setdata
 15 {
 16 public:
 17     setdata():
 18         data_(0){
 19     }
 20     setdata(int data):
 21         data_(data){
 22     }
 23     ~setdata(){}
 24 
 25     bool operator<(const setdata &data) const{
 26         return data_<data.GetData();
 27     }
 28 
 29     int GetData() const{
 30         return data_;
 31     }
 32 
 33 private:
 34     int data_;
 35 };
 36 
 37 struct mapcmp
 38 {
 39     bool operator()(const int &data1,const int &data2){
 40         return data1<data2;
 41     }
 42 };
 43 
 44 set<setdata> set_int;
 45 multiset<setdata> multiset_int;
 46 map<int,string,mapcmp> map_intstr;
 47 multimap<int,string,mapcmp> multimap_intstr;
 48 
 49 int main()
 50 {
 51     //for set
 52     set_int.insert(setdata(1));
 53     set_int.insert(setdata(20));
 54     set_int.insert(setdata(14));
 55     set_int.insert(setdata(23));
 56 
 57     cout<<"output set container data"<<endl;
 58     for(set<setdata>::iterator iter = set_int.begin();iter!=set_int.end();++iter){
 59         cout<<iter->GetData()<<" ";
 60     }
 61     cout<<endl<<endl;
 62 
 63     //for multiset
 64     multiset_int.insert(setdata(1));
 65     multiset_int.insert(setdata(20));
 66     multiset_int.insert(setdata(20));//insert 20 again.
 67     multiset_int.insert(setdata(14));
 68     multiset_int.insert(setdata(23));
 69 
 70     cout<<"output multiset container data"<<endl;
 71     for(set<setdata>::iterator iter = multiset_int.begin();iter!=multiset_int.end();++iter){
 72         cout<<iter->GetData()<<" ";
 73     }
 74     cout<<endl<<endl;
 75 
 76     //for map
 77     map_intstr.insert(pair<int,string>(9,"chen"));
 78     map_intstr.insert(pair<int,string>(2,"wang"));
 79     map_intstr.insert(pair<int,string>(13,"wu"));
 80     map_intstr.insert(pair<int,string>(7,"tang"));
 81 
 82     for(map<int,string>::iterator iter = map_intstr.begin();iter!=map_intstr.end();++iter){
 83         cout<<iter->second<<" ";
 84     }
 85     cout<<endl<<endl;
 86 
 87     //for multimap
 88     multimap_intstr.insert(pair<int,string>(9,"chen"));
 89     multimap_intstr.insert(pair<int,string>(2,"wang"));
 90     multimap_intstr.insert(pair<int,string>(13,"wu"));
 91     multimap_intstr.insert(pair<int,string>(13,"wu"));//insert wu again.
 92     multimap_intstr.insert(pair<int,string>(7,"tang"));
 93 
 94     for(map<int,string>::iterator iter = multimap_intstr.begin();iter!=multimap_intstr.end();++iter){
 95         cout<<iter->second<<" ";
 96     }
 97     cout<<endl;
 98 
 99     return 0;
100 }

　　In both map and set,I define compare function myself.

posted @ 2014-09-06 15:21  zhouyoulie  阅读(195)  评论(0)  编辑  收藏  举报