[ruby-tut] Errata / Comments

[Davis, James (NIH/CIT)]

Data structures / What can arrays do? / Array arithmetic

    Suggestion:
    Might want to mention that Array addition and
    subtraction requires the brackets.  E.g.,
        names + [ "Joel" ]
        
    
Data structures / What can arrays do? / Printing arrays
    
    Typo:
    - Remember that the nill
    + Remember that the nil
    

Data structures / Iterators / Exercises

    Suggestion: Possible exercise
        Given these parallel arrays,
            zips = [12202, 02101, 60601, 48201]
            cities = ["Albany", "Boston", "Chicago", "Detroit"]
        write a program that prompts the user for a zip code,
        then finds and prints the city name.
        
    Suggestion: Possible exercise
        Given this array,
            zip_cities = [[12202,"Albany"],[02101,"Boston"], \
                         [60601,"Chicago"],[48201,"Detroit"]]
        write a program that prompts the user for a zip code,
        then finds and prints the city name.


Data structures / Hashes / Some terminology: keys and values

    Phrasing:
    - So, in the above example, the keys are "first name",
      "last name" and "city" are some of the keys.
    + So, in the above example, "first name", "last name"
      and "city" are some of the keys.


Data structures / Hashes / Exercises

    Suggestion: Possible exercise
        Given this hash,
            zip_cities = {12202 => "Albany",
                          02101 => "Boston",
                          60601 => "Chicago",
                          48201 => "Detroit"}
        write a program that prompts the user for a zip code,
        then finds and prints the city name.  How does this
        exercise compare with the similar exercise given earlier
        for arrays?  Is an iterator needed?  This type of hash
        is referred to as an Associative Array.


Data structures / Example: Addressbook / First step: requirements

    Typo:
    - The address book contains a group of contacts .
    + The address book contains a group of contacts.
    
    Phrasing:
    - We are going to tackle these starting and the
      address structure and finishing the the addressbook.
    + We are going to tackle these starting with the
      address structure and finishing with the addressbook.


Data structures / Example: Addressbook / Third step: Persons
    
    Typo:
    - ... so we definitelly need a hash.
    + ... so we definitely need a hash.

    Suggestion:
    + Note that each person's data is stored in a hash
      variable, and the value of each "address" key is
      also stored in a hash variable.      


Typo:
- Data structures / Example: Addressbook / Excercises
+ Data structures / Example: Addressbook / Exercises


Data structures / Printing the addressbook / Phone number

    Inconsistency:
    - Phone number:
    + Phone number
    

Data structures / Printing the addressbook / Address

    Typo:
    - Finally add the address and a sepparation between the entries.
    + Finally, add the address and a separation between the entries.
    
    Typo in code:
    - # A blank line to sepparate entries.
    + # A blank line to separate entries.
    

Data structures / Sorting the addressbook / A second look at Array#sort

    Typo:
    - We know that, by defalt
    + We know that, by default

  
Data structures / Sorting the addressbook / The <=> operator

    Inconsistency:
    - The <=> operator.
    + The <=> operator

    Typo:
    - Sorting is so common, that there is an operator to simplyfy
    + Sorting is so common, that there is an operator to simplify
    

Data structures / Writing good programs / Good programming techniques

    Phrasing:
    - If you a collection of disparate data
    + If you have a collection of disparate data


More later,

- Jim -