set-clear

////////////////////////////////////////
//      2018/04/28 9:02:40
//      set-clear

// removes all elements
#include <iostream>
#include <set>
#include <functional>

using namespace std;

void print(set<int, less<int>>& s){
    set<int, less<int>>::iterator it;
    for (it = s.begin(); it != s.end(); it++){
        cout << *it << " ";
    }
    cout << endl;

}

//-------------------------

int main(){

    int ary[] = { 1, 2, 3, 2, 3, 4, 8, 2, 5, 6 };
    set<int, less<int>> s;

    s.insert(ary, ary + 10);
    print(s);

    s.clear();

    cout << "size of set s = " << s.size() << endl;
    print(s);
    return 0;
}

/*
OUTPUT:
    1 2 3 4 5 6 8
    size of set s = 0
   此行为空
*/