Installing Ruby and Rails

The installation process of Ruby and Rail on Windows, MAC and Linux are discussed detail in the following thread.

http://www.discussweb.com/ruby/4012-...s-windows.html

thanks

__________________
Prasanna Vignesh
MCPD | Web Developer

Getting Started with Ruby

Ruby is the language that is going to make everything happen. To work with Ruby, you need a text editor of the kind you already used to get the Ruby on Rails example working, such as
word pad (Start➪ Programs➪Accessories➪WordPad) or
Notepad (Start➪Programs➪Accessories➪Notepad) in Windows.

Each Ruby program should be saved with the extension .rb

__________________
Prasanna Vignesh
MCPD | Web Developer

Hello World in Ruby

To get started with Ruby and make it display a Hello World message, follow these steps:

1. Start your text editor and enter the following Ruby code:
   
   
   Code:

   puts “Hello World.”

2. Save the file as hello.rb. Make sure you save the file as a text file (select Text Document in the Save As Type drop-down), and if you are using windows WordPad or Notepad, make sure you enclose the name of the file in quotes—”hello.rb”—before saving to prevent those editors from saving the file as hello.rb.rtf or hello.rb.txt.
   
   
3. Use Ruby to run this new program and see the results. Just enter the ruby command followed by the name of the program at the command line:

C:\rubydev>ruby hello.rb

Hello World.

__________________
Prasanna Vignesh
MCPD | Web Developer

Working with Numbers in RUBY

To get started with numbers in Ruby, follow these steps:

1. Enter this Ruby code in a new file:
   
   Code:

   puts 12345
   puts 3.1415
   puts 31415.0e-4
   puts 12_345_678_987_654_321
   puts 0xddff

2. Save the file as numbers.rb.
3. Use Ruby to run numbers.rb:

__________________
Prasanna Vignesh
MCPD | Web Developer

Working with Strings in Ruby

To get started with strings in Ruby, follow these steps:

1. Enter this Ruby code in a new file, strings.rb:
   
   
   
   Code:

   puts “Hello”
   puts “Hello “ + “there”
   puts ‘Nice to see you.’
   puts %Q/How are you?/
   puts %Q!Fine, and you?!
   puts %q!I’m also fine, thanks.!
   puts “I have to say, ‘I am well.’”
   puts “I’ll also say, \”Things are fine.\””

2. Save the file as strings.rb.
3. Run strings.rb using Ruby to see the result:

__________________
Prasanna Vignesh
MCPD | Web Developer

Ruby’s reserved words:

1. __FILE
2. __ def
3. in
4. self
5. __LINE
6. __ defined?
7. module
8. super
9. BEGIN
10. do
11. next
12. then
13. END
14. else
15. nil
16. true
17. alias
18. elsif
19. not
20. undef
21. and
22. end
23. or
24. unless
25. begin
26. ensure
27. redo
28. until
29. break
30. false
31. rescue
32. when
33. case
34. for
35. retry
36. while
37. class
38. if
39. return
40. yield

__________________
Prasanna Vignesh
MCPD | Web Developer

Storing Data in Variables - Working with Variables

To get started with variables in Ruby, follow these steps:

1. Enter this Ruby code in a new file, variables.rb:
   
   
   Code:

   temperature = 36
   puts “The temperature is “ + String(temperature) + “.”
   temperature = temperature + 5
   puts “Now the temperature is “ + String(temperature) + “.”

2. Save the variables.rb file.
3. Run variables.rb to see the result:

__________________
Prasanna Vignesh
MCPD | Web Developer

Creating Constants

You can also create constants in Ruby. A constant holds a value that you do not expect to change, such as

the value of pi:

PI = 3.1415926535


IP_SERVER_SOURCE = “903.111.333.055”
IP_SERVER_TARGET = “903.111.333.056”

Unlike other languages, Ruby allows you to change the values in constants by assigning a new value to
them:
CONST = 1
CONST = 2

However, you’ll get a warning each time you do this:

constants.rb:2: warning: already initialized constant CONST

__________________
Prasanna Vignesh
MCPD | Web Developer

Interpolating Variables


To get started with interpolating expressions in double-quoted strings in Ruby, follow these steps:

1. Enter this code in a new file, doublequoted.rb:
   
   
   Quote:

   temperature = 36 puts “The temperature is #{temperature}.” temperature = temperature + 5 puts “Now the temperature is #{temperature}.”

2. Save doublequoted.rb.
3. Run doublequoted.rb:

__________________
Prasanna Vignesh
MCPD | Web Developer

Reading Text


To get started reading text in Ruby, follow these steps:

1. Enter this code in a new file, gets.rb:
   
   Quote:

   print “Please enter the temperature: “ gets chomp puts “The temperature is #{$_}.”

2. Save the file and run it.
3. Ruby displays the prompt Please enter the temperature: and then waits for a response from you:
   
   Quote:

   C:\rubydev>ruby gets.rb Please enter the temperature:

4. Enter a temperature and press Enter. Ruby reads the text that you have entered, chomps the
   newline character off the end of it, and displays the resulting text:

__________________
Prasanna Vignesh
MCPD | Web Developer

Using Operators

To get started using operators in Ruby, follow these steps:

1. Enter this code in a new file, operators.rb:
   
   
   Quote:

   value = 3 puts value value = value + 3 #addition puts value value = value / 2 #division puts value value = value * 3 #multiplication puts value value = value ** 2 #exponentiation puts value

2. Save operators.rb.
3. Run operators.rb:

__________________
Prasanna Vignesh
MCPD | Web Developer

Ruby Operators

Ruby Operators Operator Description
[ ] Array reference
[ ]= Array element set
** Exponentiation
! Not
~ Complement
+ Unary plus
- Minus
* Multiply
/ Divide
% Modulo
+ Plus
- Minus
>> Right shift
<< Left shift
& Bitwise And
^ Bitwise exclusive Or (Xor)
| Regular Or

Comparison operators:

<= Less than or equal to
< Less than
> Greater than
>= Greater than or equal to

Equality and pattern match operators:

<=> Less than, equal to, greater than
== Equal to
=== Tests equality in a when clause of a case statement
!= Not equal to
=~ Regular expression pattern match
&& Logical And
|| Logical Or
.. Inclusive range
... Exclusive range
? Ternary if
: Else

Assignment

= Normal assign
%= Modulus and assign
/= Divide and assign
-= Subtract and assign
+= Add and assign
*= Multiply and assign
**= Exponent and assign
defined? True if symbol defined
not Logical negation
and Logical composition
or Logical composition

Statement modifiers

if
unless
while
until

begin/end Block expression

__________________
Prasanna Vignesh
MCPD | Web Developer

Working with Arrays

There are plenty of ways to work with data in Ruby. Next up is to store it in arrays. Arrays act as groups of variables, and you can access each variable in an array with an index number.

For example, to create an array, you use the [] operator like this:

array = [1, 2, 3]

This creates an array with three elements, 1, 2, and 3. You access those elements using an array index like this:

Note that the first element in the array corresponds to array index 0, not 1, and the second element is at index 1, the third at index 2, and so on. You can also assign values to arrays, using the array index:

As you know, Ruby variables can store text strings as well as numbers, and you can store both in arrays.

Here’s an example:

array = [“Hello”, “there”, “sweetie”, 1, 2, 3]

This creates an array filled with six elements, three of which are text and three of which are numbers:

__________________
Prasanna Vignesh
MCPD | Web Developer