Array of variable length of non-POD element of type 'set <int>'

Question

I have no idea what the problem is.

#include <iostream>
#include <algorithm>
#include <fstream>
#include <set>
using namespace std;

int main() {
    ifstream infile("meeting.in");
    int FF, NumPaths;
    infile >> FF >> NumPaths;
    int Paths[NumPaths][4];
    set<int> Bessie_Times[FF];
    set<int> Elsie_Times[FF];
    for(int i=0;i<NumPaths;i++)
    {
        infile >> Paths[i][0] >> Paths[i][1] >> Paths[i][2] >> Paths[i][3];
    }
    sort(Paths,Paths+NumPaths);
}

In these lines, I get the following errors:

    int Paths[NumPaths][4];

The array type 'int [4]' is not assigned

    set<int> Bessie_Times[FF];

Error 1: array initializer must be a list of initializers

Error 2: array of variable length of non-POD element of type 'set'

Does anyone know what causes this? I searched around, but could not find anything that solved the problem. I assume that I am trying to use a variable type where I should not be, but I cannot find an instance of this.

Answer 1

g++ ( ). , . ++ stdlib:

#include <iostream>
#include <algorithm>
#include <fstream>
#include <set>
#include <array>

using namespace std;

int main()
{
  ifstream infile("meeting.in");
  int FF, NumPaths;
  infile >> FF >> NumPaths;

  std::vector<array<int, 4>> Paths(FF);
  std::vector<set<int>> Bessie_Times(FF);
  std::vector<set<int>> Elsie_Times(FF); 

  for(int i = 0; i < NumPaths; i++)
  {
    infile >> Paths[i][0] >> Paths[i][1] >> Paths[i][2] >> Paths[i][3];    
  }  

  sort(Paths.begin(), Paths.end());

  return 0;
}

; ,

sort(Paths[i].begin(), Paths[i].end());

Answer 2

int Paths[NumPaths][4];//Array type 'int[4]' is not assignable

, , . , ++ . , :

int Paths[NumPaths][4]; // wrong

int *Paths[4]; // right
for (int i = 0; i < 4; i++)
  Paths[i] = new int[NumPaths]; 

set<int> Bessie_Times[FF];//Error 1: Array initializer must be an initializer list Error 2: variable length array of non-POD element type 'set<int>'`

, :

set<int> Bessie_Times[FF]; // wrong
set<int> *Bessie_Times = new set<int>[FF]; // right

, :

delete Paths[][];
delete BessieTimes[];