Attempting to reference a deleted function, using set and custom compare lambda function

Question

I want to create a sorted list without sorting it by the sum of digits of each number. Therefore I chose a set, but with a custom compare function. I did not use set before, but I've read a lot about it and I thought it'd be simple to use, but I don't really understand my error: Attempting to reference a deleted function

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <fstream>
#include <cstring>
#include <cmath>
#include <iomanip>
#include <vector>
#include <stack>
#include <algorithm>
#include <unordered_map>
#include <map>
#include <utility>
#include <queue>
#include <set>
#include <string>
#include <sstream>

using namespace std;

ifstream f("input.txt");
ofstream g("output.txt");


int sumCif(int x) {
    if (x < 10) return x;
    return x % 10 + sumCif(x / 10);
}

int main()
{
    int x;
    auto cmp = [](int a, int b) {
       if (sumCif(a) < sumCif(b)) return true;
        return a > b;
    };

    set<int, decltype(cmp)>s;

    while (f >> x)
        s.insert(x);
    
    for (auto& i : s)
        g << i << " ";

    return 0;
}

I recently downloaded again visual studio, I didn't think it would use such an old version of c++ — fantatraieste, Jun 08 '23 at 06:52
Look at Build Output, the error messages there are more informative. Post the error message as a pre-formatted text in the question. — 273K, Jun 08 '23 at 06:54
What would really help if you have a bit of code (in text) that we can copy into our compilers to reproduce your issue. — Pepijn Kramer, Jun 08 '23 at 06:54
Check https://stackoverflow.com/questions/2620862/using-custom-stdset-comparator. Try the solution for c++11. — Albin Paul, Jun 08 '23 at 06:54
you must find the tab in your ide where the complete compiler output is shown. The summary in your screenshot is close to useless. Its a fancy thing that you can click and the IDE takes you to the line with the error. Your screenshot is not clickable and only the compiler output has the complete information. Please [edit] the question — 463035818_is_not_an_ai, Jun 08 '23 at 08:16

lbbc · Answer 1 · 2023-06-08T10:06:00.447

0

set<int, decltype(cmp)> s(cmp);

lambda disables the default constructor, so you need to explicitly pass the cmp

edited Jun 08 '23 at 10:06

answered Jun 08 '23 at 10:01

lbbc

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Attempting to reference a deleted function, using set and custom compare lambda function

1 Answers1