Thread: Reading a class object with cin.

  1. #1
    Registered User
    Join Date
    Jan 2014

    Reading a class object with cin.

    I have used member variables and operated on them with the help of member functions. Bu in one of the examples in C++ Primmer i found something like this:

    Sales_item book;               \\book is an object of class Sales_item
    How is it possible to read the object and output that after processing without using '.' operator and any member variable/function? I tried looking into the header "Sales_item.h" but didn't understand that.

  2. #2
    Registered User
    Join Date
    Oct 2006
    You'll need to overload the >> operator for your class type. Something like this:
    std::istream& operator>>(std::istream& is, Sales_item& item)
      is >> item.some_field;
      is >> item.some_other_field;
      return is;
    And then do something similar with the << operator and std::ostream.

    Of course this is a very oversimplified example. You need to check for errors at every step of the way.
    What can this strange device be?
    When I touch it, it gives forth a sound
    It's got wires that vibrate and give music
    What can this thing be that I found?

  3. #3
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    operator overloading -
    Scroll down to "Stream extraction and insertion"
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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