No operator >> matches these operands... why?

Question

I'm having some problems reading a vector of ints from a file... and it's the first time this happens to me and I have tried everything. Here is a part of my code:

#include<stdio.h>
#include<conio.h>
#include<iostream>
#include<vector>
#include<string>
#include<fstream>


int m;
std::vector<int>a[100];
std::vector<int>b[100];
int main()
{
    std::ifstream file("data.in");
    file>>m;
    int i;

    for( i = 0; i<m/2; i++ )
         file>>a[i]>>b[i]; 



    return 0;
}

Why won't it work? :(

Answer 1

std::vector<int>a[100];

declares an array containing 100 vectors. So a[i] is a vector, not an int. You can't read a vector directly from input.

If you want vectors of size 100, instead of an array of 100 vectors, the syntax is

std::vector<int> a(100);