A classy solution

• Task 1, How will I store the word information?
  • Structures are nice, but
  • They do not automatically initialize themselves
  • The user (other programmer) can mess with the data fields
    • And I have no protection to make sure they don't mess them up.
    • For example, they might not like "dan" as a word, so they set the count to be -100
  • And the functions are not tightly grouped with the data.
• A better solution is a class.
• Classes
  • Have member data - or data fields just like structures.
  • They also have member functions.
    • These are the basic operations you can perform on that data.
  • We will deal with some theory soon, but let's make a WordT class
• One bit of theory
  • An Abstract Datatype is a data type whose properties (domain and operations) are specified independently of any particular implementation. (P 596)
  • In C++ classes are used to implement ADT's
• For our WordT
  • What is the domain, or what data will we store
    • The word, a string.
    • The number of times we have seen that word, probably a size_t
  • What are the operations?
    • Set and get the word
    • Increment the count
    • Get the count.
    • These are generally classified as
      • Constructors
      • Getters or Observers
      • Setters or Transformers
• Class syntax
  • Classes have access modifiers
    • These are instructions that tell the compiler "who" has access to the members.
    • These are either public, private, or protected.
    • Ignore protected for now.
    • Public means anyone can access the member
    • Private means only instances of the class can access the member.
    • By default everything in a class is private.
    • But we will always specify modifiers.
  • Unless you have a good reason, all data is private.
    • Provide member functions to get and set the data.
  • Finally the syntax

    class identifier {
        access modifier:
            member list
        access modifier:
            member list
    }; 

  • In this case, a member list is
    • function prototypes
    • variable declarations.
• Class Scope
  • When inside of a class (member function) you have access to all other members.
    • Data and functions.
  • To place a function in the class scope use the scope operator.
• Let's build the WordT as an example.