Ruby_Notes.md

Ruby Notes

Getting Started with the Basics

Printing to the Command Line

• puts method - Prints a string to the cli with a break at the end
  • Ex: puts "Hello World" --> Hello World\n
• print method - Prints a string to the cli
  • Ex: puts "Hello World" --> Hello World
• p method - Prints a string literal to the cli
  • Equilvalent to mystring.inspect
• Some useful string related methods:
  • .upcase, .downcase, .capitalize, and .swapcase
  • .include?
  • .length or .size
  • .reverse
  • .empty? or .nil?
  • mystring[3] or mystring.slice(3)
  • mystring[3, 6] or mystring.slice(3, 6)
  • • .to_i or .to_f - Converts to an integer or float
  • mystring.gsub(/s/, "th")
  • mystring.split(" ")

Comments

The # character is used for single line comments.

Multi-line comments are written as follows.

puts "Hello World"
=begin
Stuff in here is a multi-line comment.
At least it is as of this line.
=end

Parallel Variable Assignment

Variables can be assigned as used in parallel (written in one line) as follows:

a, b, c = 10, 20, 30
p a, b, c

=begin
Output:
10
20
30
=end
# Variable Swaping
a, b = b, a

String Interpolation

Example:

p "Hello #{name}!"

gets and chomp methods

• gets retrieves a command line inputs from the user
• chomp - removes an extra line from the end of a string (from gets for example)

Getting Under the Hood with Ruby

Numbers

Numbers in Ruby are either integers or floating point numbers. All numbers are objects and can therefore have methods called upon them. For example:

1.next # = 2
p 1.to_s # "1"
1.class # Fixnum
1.01.class # Float
999999999999999999999999999999999999.class # Bignum
1.odd? # true
1.even? # false
3.between?(1, 5) # true
1.5.floor # = 1
1.5.ceil # = 2
3.1415.round # = 3
3.1415.round(3) # = 3.142
-381.abs # = 381

Equality/Comparison

Basically the same as other common programming languages. Just look it up if it behaves in an unexpected manner.