The WordArrayT

Objectives

We would like to :

Implement a static array to hold words.

Notes

We discussed a static array of WordCountT in our initial design
- Data:
  - size_t size, capacity
  - WordCountT data[MAX_WORDS]
- Methods:
  - constructor
  - Size - to get the current elements
  - Capacity - to get the capacity
  - PushBack(WordCountT) to add a word
  - [] to access the array
  - at to access the array
- Take a look at WordArrayT.h.
  - Note: using DataT = WordCountT;
    - This makes DataT a nickname for WordCountT
    - This makes it generic so I can change the data type by changing this line.
    - This is the modern form
    - it could also be done with typedef WordCountT DataT;, but you should use the other form.
    - It could also be done with a #define BUT DO NOT DO THAT.
  - Note I declare MAX_WORDS outside of the class.
  - Note I perform most of the initialization in the declaration
    - I really don't need a constructor because of this.
    - The compiler will write one for me.
    - Which will be the default constructor, which does nothing.
- The implementation of [] is interesting
  - There are two forms
    - One that returns a constant reference.
    - One that returns a reference.
- The constant reference
  - This is for the right hand side (RHS).
  - ```
  WordArrayT words;
  WordCountT word;
  ...
  word = words[3]; 
```
- It gives me back an array entry that I will not change.
- The prototype is const DataT & operator [] (size_t index) const
- You could also use the modern constexpr, but I have not yet learned that.
- The function just returns the data at the index.
- This is dangerous, but convention says it is the user's responsibility to get the index right.
- The RHS at
  - Same semantics
  - But checks to see if the index is valid.
  - We have a problem here, what do we return if the index is not valid?
    - For now we will return data[0], but this is bad.
    - Later we will learn about exceptions, which is what we should do here.
- The reference (or left hand side, LHS);
  - ```
  WordArrayT words;
  WordCountT word;
  ...
  words[3] = word; 
```
- This allows us to change an element in the array.
- The prototype is DataT & operator [] (size_t index);.
- The LHS at function is the same.
- Surprisingly these functions are duplicates here, but perhaps not for other structures.
See WordArrayT.cpp.