set

#include <iostream>using namespace std;#include <set>int main(){set<int> si;int userid[5]={3,4,7,7,8};for (int i=0; i<5; i++){si.insert(userid[i]);}set<int>::iterator it;it = si.begin();while(it!=si.end())cout << *it++ << ' ';cout << endl;cout << "user 3:" << (si.find(3)!=si.end()) << endl;cout << "user 5:" << (si.find(5)!=si.end()) << endl; return 0;}