ruby-notes

! Everything is an object

Comments #

Numbers

  x.to_f > convert to float
  x.to_i > convert to integer

  x.even? > returns true if number is even
  x.dd? > test for odd

Strings
  Concatenation
    s + s
    s << s
    s.concat(s)

  Substrings
    s[index]
    s[start..end]
    s[start, end]
    s[-index]

  Escape  ! only works inside "", not inside ''
    \\  #=> Need a backslash in your string?
    \b  #=> Backspace
    \r  #=> Carriage return, for those of you that love typewriters
    \n  #=> Newline. You'll likely use this one the most.
    \s  #=> Space
    \t  #=> Tab
    \"  #=> Double quotation mark
    \'  #=> Single quotation mark

  Interpolation   ! only works inside "", not inside ''
    name = "Odin"

    puts "Hello, #{name}" #=> "Hello, Odin"
    puts 'Hello, #{name}' #=> "Hello, #{name}"

  Common string methods
    s.capitalize
    s.include?()
    s.upcase
    s.downcase
    s.empty?
    s.length
    s.reverse
    s.split
    s.strip                 # Strips extra spaces
    s.sub(old s, new s)     # string substitution
    s.gsub(old s, new s)    # Not sure how this is different from the last
    s.insert(index, s)
    s.prepend(s, s)         # Add to front

  Converting to string
    x.to_s
  
Symbols
  A different kind of string; Stored in memory only once amking them faster
    in some situations; Example use case: keys in hashes

  To create: put a colon before a string
    :my_symbol

  ! Note: not exactly a variable name, not exactly text
          considered as code, not data

Booleans
  true, false, nil

  nil: represents "nothing"; everything has a return, including error messages
    and nil if something doesn't have one