swan lin's List: Ruby Stduy

• Objective: 
   To get you up-to-speed in Core Ruby programming. Learning and asking questions as a group 'jump-starts' the Ruby learning process.

  • ruby lesson index

• Keywords can't be used as variable names. def is a keyword

• does not have anything in it at all; we call that an empty string.
• puts 'It\'s my Ruby' 

  • \ 的作用相当于一个 ‘
• n Ruby, strings are mutable. They can expand as needed, without using much time and memory. Ruby stores a string as a sequence of bytes.
• The command output string is sent to the operating system as a command to be executed

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• Ruby integers are objects of class Fixnum or Bignum. The Fixnum and Bignum classes represent integers of differing sizes. Both classes descend from Integer (and therefore Numeric). The floating-point numbers are objects of class Float, corresponding to the native architecture's double data type.

• Free format
• Case sensitive
• Comments - Anything following an unquoted #, to the end of the line on which it appears, is ignored by the interpreter. Also, to facilitate large comment blocks, the ruby interpreter also ignores anything between a line starting with =begin and another line starting with =end
• Statement delimiters
• But in Ruby, all of these are true; in fact, everything is true except the reserved words false and nil.

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• Press the F8 key to open an output window
• Ctrl+Shift+I - this opens the Indentation Settings window
• All Ruby source files have the .rb file extension
• Foo class has name foo.rb
• puts (s in puts stands for string; puts really means put string)
• g) > simply writes onto the screen whatever comes after it,
• simply writes onto the screen whatever comes after it
• a. Parentheses are usually optional with a method call. These calls are all valid:
  foobar
  foobar()
  foobar(a, b, c)
  foobar a, b, c
• everything from an integer to a string is considered to be an object
• To use a method, you need to put a dot after the object, and then append the method name.
• Some methods such as puts and gets are available everywhere and don't need to be associated with a specific object.
• provided by Ruby's Kernel module
• When you run a Ruby application, an object called main of class Object is automatically created. This object provides access to the Kernel methods.
• I am using single quotes around Hello. ' is more efficient than "
• String literals are sequences of characters between single or double quotation marks
• Ruby is an interpreted language

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• Ruby has been described as an absolutely pure object-oriented scripting language and a genuine attempt to combine the best of everything in the scripting world.
• Yukihiro Matsumoto (or "Matz" as he's known online) is the creator of Ruby

• Yukihiro Matsumoto, commonly known as 'Matz' created the Ruby language in 1993

• We shall be referring to the documentation here - http://www.ruby-doc.org/core/
• Constants begin with capital letters. Example PI, Length

• It is my observation that if one learns a programming language along with a group and with set targets every day; one learns faster.

• RubyLearning.com is a thorough collection of Ruby Study Notes for those who are new to the Ruby programming language and in search of a solid introduction to Ruby's concepts and constructs - ruby-lang.org.

• an identifier starts with a capital letter, it is a constant
• starts with @, it is an instance variable
• starts with @@, it is a class variable.
• starts with a dollar sign ($), it is a global variable
• Method names
• start with capital letters
• Ruby doesn’t have keyword parameters,
• In Ruby, everything except nil and false is considered true.
• Singleton methods are per-object methods. They are only available on the Object you defined it on.

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• In Ruby, anything on a line after a hash mark is a comment and is ignored by the interpreter
• __FILE__ is the magic variable that contains the name of the current file.
• $0 is the name of the file used to start the program.

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• Ruby uses the good object-oriented approach of keeping data sort-of hidden away.

• Ruby’s response => nil tells us that it knows we’re done defining the method
• h to take a name as a parameter.
• saying is “If the name isn’t supplied, use the default name of "World"”.
• @name. This is an instance variable, and is available to all the methods of the class

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• puts always returns nil, which is Ruby’s absolutely-positively-nothing value.
• puts is the basic command to print something out in Ruby.
• In Ruby ** is the way you say “to the power of”
• floating-point number.

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