SE 498 Sample Code

echoinput.rb: echo standard input to standard output (with line numbers); type
```
        ruby echoinput.rb < echoinput.rb
```
at the command prompt (after installing Ruby) to display the program.
sum.rb: compute sum of entered numbers. Enter
```
        ruby sum.rb
        5
        4
        3
        Control-Z
```
(where the last line is holding down the control key and pressing a Z) to print a 12.
gpa.rb: compute GPA
phones.rb: simple phone book based on arrays; to test, run irb and type
```
        irb> load 'phones.rb'
        irb> test_phone_book
```
revised-phones.rb: revised phone book using hash tables.
gpa.rb: computing semester gpa from input strings; illustrates string and array processing.
csv-select: Ruby program to select specified field from input containing comma-separated values. This is based on a state machine (also available in visio format). The file data.csv can be used for testing. This also illustrates command-line argument processing (see main) and making a stand-alone program (see the first line in the file).

Overloading operator ==:

        class Pair
          attr_reader :x, :y
          attr_writer :x, :y
          # two Pairs are defined to be the same if their products are:
          def ==(other)
            @x * @y == other.x * other.y
          end
        end

Using it:

        irb(main):042:0> a = Pair.new; a.x = 5; a.y = 6
        => 6
        irb(main):043:0> b = Pair.new; b.x = 3; b.y = 10
        => 10
        irb(main):044:0> a == b
        => true
        irb(main):045:0> b.y = 9
        => 9
        irb(main):046:0> a == b
        => false

vote.zip: Rails project based on the Rails voting demo.
vote-note4.zip: Rails project based on the Note 4 of the Rails voting demo.
todo.zip: Rails project from CoffeeScript Programming with jQuery, Rails, and Node.js - illustrates using jQuery with Rails 4.2.1 and Ruby 2.0.0.