input vectors outside of main function c++

Question

I am trying to get an input to a matrix by placing the whole thing as in a function outside of main (), as follows:

    void input_matrix(int row, int col){
std::vector<std::vector<int>> matrix;
  
  for (int m=0; m<row; m++){
    for (int n=0; n<col; n++){
      std::cin >> matrix[m][n];
    }
  }
  return matrix;
}

somehow the compiler doesn't like me inputing the matrix here, any solutions?

Answer 1

There are two errors in your code.

1. The return type of the function input_matrix() is void which needs to be changed to vector<vector<int> >
2. Initialize the matrix with proper space.

The corrected code would look something like this:

std::vector<std::vector<int> > input_matrix(int row, int col){
    std::vector<std::vector<int> > matrix(row, std::vector<int>(col));
  
    for (int m=0; m<row; m++){
        for (int n=0; n<col; n++){
            std::cin >> matrix[m][n];
        }
    }
    return matrix;
}