Ruby By Examples

The book is broken down into sections. Each section deals with a Ruby language theme, giving examples, from basic to advanced. A full list of Ruby methods can be found here. Basics Strings Example-001: String Length puts 'That is an object'.size # => prints 17 Example-002: Reversing puts 'This is not a palindrome'.reverse # => prints 'emordnilap a ton si sihT' Example-003: Single substitution puts 'a banana'.sub('a', '*') # => prints '* banana' Example-004: Global substitution puts 'a banana'.gsub('a', '*') # => prints '* b*n*n*' Numbers Example-001: Use the times method to run code over and over 5.times do puts 'Loop' # => prints 'LoopLoopLoopLoopLoop' end Example-002: Calculating absolute value puts -10.abs # => prints 10 Arrays Example-001 arr = [['0','0','0'],['0','$','0'],['0','0','0']] puts arr[1][1] Example-002 a = [1, 2, 3, 4].shuffle a.each {|e| puts e} Example-003 a = %w|this is a string array| puts a.join(' ') Example-004 a = (0..10).to_a a.map! {|x| x**2} a.each {|e| puts e} # 0, 1, 4, 9, 16... Example-005 items = ['random', 3, Math::PI, 'items'] puts items.index(3) # 1 puts items.include?(Math::E) # false Hashes books = {'978-0140449266' => 'The Count of Monte Cristo', '978-0140439243' => 'The Man in the Iron Mask' } puts books['978-0140439243'] # The output is 'The Man In The Iron Mask' more_books = {} more_books['978-1593081485'] = 'The Three Musketeers' Operators :: (Scope Operator) Example-001 MR_COUNT = 0 # constant defined on main Object class module Foo MR_COUNT = 0 ::MR_COUNT = 1 # set global count to 1 MR_COUNT = 2 # set local count to 2 end puts MR_COUNT # this is the global constant puts Foo::MR_COUNT # this is the local "Foo" constant Example-002 CONST = ' out there' class Inside_one CONST = proc {' in there'} def where_is_my_CONST ::CONST + ' inside one' end end class Inside_two CONST = ' inside two' def where_is_my_CONST CONST end end puts Inside_one.new.where_is_my_CONST # out there inside one puts Inside_two.new.where_is_my_CONST # inside two puts Object::CONST + Inside_two::CONST # out there inside two puts Inside_two::CONST + CONST # inside two out there puts Inside_one::CONST # #<Proc:0xedfa98(irb):3> , reference to the procedure puts Inside_one::CONST.call + Inside_two::CONST # in there inside two [ ] Example-001 a = [1, 2, 3, 4] # array creation puts a[0] # array indexing puts a[-1] # same as a[a.length-1] Example-002 s = 'a meaningless string' puts s[10] # prints 'e' Example-003 p = proc {|arg| puts 'You called me with ' + arg.to_s} p['a string arg'] # same as proc.call ** + - ! ~ * / % << >> & | ^ > >= < <= <=> == === != =~ && .. ... = ( += -= ) not and or Intermediate Modules and Procedures Classes and Methods Names, Variables, Constants and Symbols Advanced Active record Sockets Example-001 # daytimeserver.rb puts'=========================================' require 'socket' puts'== daytime server ==' # Open a socket to a local daytime server, read, and print. print TCPSocket.open('129.6.15.28', 'daytime').read puts'=========================================' Example-002 # socketmethods.rb require 'socket' mySocket = TCPSocket.new( 'www.wikibook.com', 80 ) puts'===================================' # Returns information on this connection's peer socket as a struct # sockaddr packed into a string. strinfo = mySocket.getpeername puts 'strinfo: '+strinfo # Returns true if query returns numeric address not host name. puts BasicSocket::do_not_reverse_lookup puts'===================================' # Returns information on s as a struct sockaddr packed into a string. strinfo = mySocket.getsockname puts 'strinfo: '+strinfo puts'===================================' # Gets the specified socket option. optval = mySocket.getsockopt(Socket::SOL_SOCKET,Socket::SO_REUSEADDR) puts 'optval: '+optval.inspect optval = optval.unpack "i" puts 'optval: '+optval.inspect optval = mySocket.getsockopt(Socket::SOL_SOCKET, Socket::SO_LINGER) puts 'optval: '+optval.inspect optval = optval.unpack "ii" puts 'optval: '+optval.inspect # Sets reverse_lookup status BasicSocket::do_not_reverse_lookup=true # Sets the specified socket option. mySocket.setsockopt(Socket::SOL_SOCKET,Socket::SO_REUSEADDR, true) optval = mySocket.getsockopt(Socket::SOL_SOCKET,Socket::SO_REUSEADDR) puts 'optval: '+optval.inspect optval = optval.unpack "i" puts 'optval: '+optval.inspect puts'===================================' # mySocket.shutdown(2) # 0 shuts down receiving, 1 sending, and 2 both. puts 'mySocket: '+mySocket.inspect puts'===================================' # Returns true if query returns numeric address not host name. puts BasicSocket::do_not_reverse_lookup puts'===================================' Ruby programming language R 0%