Question

let say that i have a file

ID  Name    Month   Actual Quantity     Desired Quantity    Cost 
2   pepsi             1                        1                3.3
3   pepsi             2                        3                5.3

how would i read that into a vector called vector<Item> items; where Item is a class that consists of those names as listed in the list. i have a set() methods for all of them but how would i read one of each values and set it for example setID() and its value and if it is empty put a value -1. What i have so far is just a basic file open

char file_name[81];
  cout<<"Enter a file to open (ex: file.txt): ";
  cin.ignore();
  flush(stdin);
  cin.getline(file_name, 81);
  ifstream input(file_name);

should i use a istringstream or what?

UPDATE:

  char file_name[81];
  cout<<"Enter a file to open (ex: file.txt): ";
  cin.ignore();
  cin.getline(file_name, 81);
  ifstream input(file_name);
  string line;
  getline(input,line);
  while (getline(input,line)){

BUT I get an error: statement cannot resolve address of overloaded function at line : ifstream input(file_name)

Answer 1

They way I would do is is to start writing a suitable input operator:

std::istream& operator>> (std::istream& in, Item& item) {
    ...
}

Once this operator is in place, you can read the file using something like this:

std::vector<Item> items;
input.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
std::copy(std::istream_iterator<Item>(input), std::istream_iterator<Item>(),
          std::back_inserter(items));