c 2b 2b set comparator

1#include <bits/stdc++.h>
2#include <iostream>
3#include <vector>
4#include <algorithm>
5#include <set>
6
7using namespace std;
8//set mentains internally the ascending order of these numbers
9void setDemo()
10{
11	set<int> S;
12	S.insert(1);
13	S.insert(2);
14	S.insert(-1);
15	S.insert(-10);
16	S.erase(1);//to remove an element
17	
18	//Print all the values of the set in ascending order
19	for(int x:S){
20		cout<<x<<" ";
21	}
22	
23	//check whether an element is present in a set or not
24	auto it = S.find(-1);//this will return an iterator to -1
25	//if not present it will return an iterator to S.end()
26	
27	if (it == S.end()){
28		cout<<"not Present\n";
29	}else{
30		cout <<" present\n";
31		cout << *it <<endl;
32	}
33	//iterator to the first element in the set which is
34	//greater than or equal to -1
35	auto it2 = S.lower_bound(-1);
36	//for strictly greater than -1
37	auto it3 = S.upper_bound(-1);
38	//print the contents of both the iterators
39	cout<<*it2<<" "<<*it3<<endl;
40}
41	
42int main() {
43	setDemo();
44	return 0;
45}

1set<int, less<int>> st;
2// or
3set<int, greater<int>> st;
4// c++ 11
5auto cmp = [](int a, int b) { return ... };
6set<int, decltype(cmp)> s(cmp);