Section 10.6 Member versus Nonmember Functions

Class:

• A data type that combines data and functions for operating on the data.
  
• Example:  string is a class.

Object:

• A member/instance of the class.
  
• Example:  string  aWord;    //aWord is an object, string is the class.

Classes have data and functions:

• aWord ="Fred";  //the data is "Fred"
  
• aWord.length()  //length is a function that can be applied to a member of the class.
  
• Notation:   object_name.member_function()

So what?

• Convenience of bundling related data and functions that operate on it.
• Abstraction: lift the features of strings above the technicalities of how they are implemented.
• An essential component of large system development.
• Examples of possible objects:
  • A matrix
  • A student record
  • A radar interface

ifstream and ofstream as classes

• The classes:
  • ifstream:   used for input from a file.
  • ofstream:  used for output to a file.
• The object: a file stream variable.
• Member functions: .open, .close, .getline.
  E.g.
    ofstream  fout;
    fout.open("out.txt");