set-find

////////////////////////////////////////
//      2018/04/28 18:53:08
//      set-find

// find a given element
#include <iostream>
#include <set>
#include <iomanip>
#include <string>

using namespace std;

template<class T>
class Member{
private:
    T first, last;
public:
    Member(T l, T f) :first(f), last(l){}
    void print() const{
        cout.setf(ios::left);
        cout << setw(15) << first << " " << last << endl;
    }

        friend bool operator <(const Member& m1, const Member& m2){
        return m1.last < m2.last;
    }
    friend bool operator == (const Member& m1, const Member& m2){
        return m1.last == m2.last;
    }
};
//======================
int main(){

    typedef Member<string> M;
    typedef set<M, less<M>> S;
    M m("Forst", "Robert");
    S s;

    s.insert(m);
    s.insert(M("Smith", "John"));
    s.insert(M("Amstrong", "Bill"));
    s.insert(M("Bain", "Linda"));

    S::iterator it = s.begin();
    while (it != s.end()){
        (it++)->print();
    }

    it = s.find(m);
    if (it == s.end()){
        cout << "element is not found." << endl;
    }
    else{
        cout << "element is found:";
        (*it).print();
    }

    return 0;
};

/*
OUTPUT:
    Bill            Amstrong
    Linda           Bain
    Robert          Forst
    John            Smith
    element is found:Robert          Forst
*/