compilation error with unordered multiset in codeblocks17.12

Question

1.error:unordered multiset is not declared in this scope 2.everything is alright except that unordered_multiset a code.

#include<bits/stdc++.h>
#define ff first
#define ss second
#define all(c) c.begin(), c.end()
#define present(container, element) (container.find(element) != container.end())
#define cpresent(container, element) (find(all(container),element) != container.end())
#define sz(a) int((a).size())
#define pb push_back
#define loop(start,end) for(int i=start;i<end;i++)
#define ll long long int
#define pii pair < int , int >
#define mset(x,v) memset(x, v, sizeof(x)) //search it
using namespace std;
typedef vector< int > vi;
typedef vector< vi > vvi;
typedef pair< int,int > ii;

int main ()
{
    ios_base::sync_with_stdio(false);cout.tie(0);cin.tie(0);
    int n;
    int q;
    cin>>n;cin>>q;
    unordered_multiset <int> s;

}

Delete all lines from `#include` to `using namespace std;` inclusive. Then add just the headers needed; edit the question to remove unnecessary macros and repost. — Richard Critten, Jan 09 '20 at 17:07
**Recommended reading:** [Why should I not #include ?](https://stackoverflow.com/q/31816095/560648) — Lightness Races in Orbit, Jan 09 '20 at 17:20

score 4 · Answer 1 · answered Jan 09 '20 at 17:10

If you use the correct headers (in this case #include <unordered_set>) rather than the abomination that is <bits/stdc++.h> then gcc will probably helpfully tell you that you need to enable c++11 to use that header.

You need to pass -std=c++11 on your compiler command line to enable c++11 features.

Unrelated but all those #defines are really not a good idea and using namespace std can cause issues too.

compilation error with unordered multiset in codeblocks17.12

1 Answers1