This document provides an introduction and overview of the Ruby programming language. It discusses installing Ruby on Windows and Mac systems, data types including numbers, strings, and arrays. It also covers variables, arrays, iterators, methods including built-in and user-defined methods, and flow control including if/else conditional statements and while loops. The document encourages comments and feedback.

1. A Brief Introduction to Ruby : P1
(Book Review of “Learn to Program”)
Brady Cheng
http://bradyisstudying.blogspot.tw/

2. Agenda
Install
Comment
Data Types
Variables, Arrays, and Iterators
Methods
Flow Control

3. Install
For Windows
http://rubyinstaller.org/
For Mac
Build-in
I strongly recommend you to use Mac or Linux to develop Ruby programs.
But in this tutorial, I am gonna use Windows since I am stiff-necked guy 

4. Comment
Comment in Ruby is similar to Perl
Ruby Perl
# comment a line # comment a line
=begin =pod
Comment a block Comment a block
=end =cut

5. Data Types
Numbers puts 1+2 #3
Integer print puts 2*3 #6
puts 5-8 #-3
Float puts 9/2 #4
Letters puts 9.to_f/2 #4.5
String
Cast to float
--------------------------
puts ‘Enter a string’ #Enter a string More:
puts gets.chomp #input from keyboard .to_i
puts 'ha'*3 #hahaha .to_s
puts=<STDOUT>
Repeat 3 times gets=<STDIN>
chomp=delete last char

6. Variables, Arrays, and Iterators
In C/C++, we write int a = 1; in Perl, we write $a = 1; in
Ruby…
a= 1
Yes, just write a
a= 1
b = ‘2’
c = a.to_s + b #12
Cast a to string
Add(+) = conj strings

7. Variables, Arrays, and Iterators
Arrays
[ele1, ele2, ele3]
Some array methods
.pop
.push
.join(‘join string’)
.last
.length

8. Variables, Arrays, and Iterators
There is a special array method : each
iterator
An array with 3 elements
color= [‘R', 'G', 'R']
color.each do | c | | c | = variable in this
puts “color=” + c do…end block
end
Output=
color=R
color=G
color=B

9. Methods
If objects(variables, arrays, …) are nouns in
English, then methods are verbs!
int=noun
We say “int, convert to string” to_s=verb
int.to_s
Sometimes we just say a verb without any noun, ie. GO!
gets
User defined methods

10. Methods
Some fancy string methods
.reverse
.upcase
.downcase
.swapcase
.capitalize
.center (width)
.ljust width
.rjust width

11. Methods
Some number methods
** #exponential
% #modular
.abs #absolute value
rand(number) #generate a random number
srand(seed) #generate a random seed

12. Methods
More on user defined methods, similar to Python!
def functionName (arg1, arg2)
#do something
return ret_val
end
Actually we don’t have to
return because….
Case1: the function doesn’t
have to return
Case2: the last line is the
default return value

13. Flow Control
Conditional flow control
Looping flow control
if condition1 while condition
#do something #do something
elsif condition2 end
#do something
else
#do something
end
Don’t forget end

14. The End
The first part is over, please wait for the second part
Any comments would be appreciated
Welcome to my study page
http://bradyisstudying.blogspot.tw/