ruby programs

Author: saikiranmothe

2009-bookofruby.pdf

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+puts 'hello world'

ch1/1helloworld.rb

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+print('Enter your name: ' )
+name = gets()
+puts( "Hello #{name}" )

ch1/2helloname.rb

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+def showname
+   return "Fred"
+end
+  
+puts "Hello #{showname}"
+puts( "\n\t#{(1+2) * 3}\nGoodbye" )

ch1/3string_eval.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+# Calculate tax on a fixed sum
+
+subtotal = 100.00
+taxrate = 0.175 # one zero only before decimal point
+tax = subtotal * taxrate
+puts "Tax on $#{subtotal} is $#{tax}, so grand total is $#{subtotal+tax}"

ch1/4calctax.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+# Prompt user for a sum then calculate tax on that sum
+
+taxrate = 0.175 
+print "Enter price (ex tax): "
+s = gets
+subtotal = s.to_f
+if (subtotal < 0.0) then
+	subtotal = 0.0 
+end
+tax = subtotal * taxrate
+puts "Tax on $#{subtotal} is $#{tax}, so grand total is $#{subtotal+tax}"

ch1/5taxcalculator.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+# Create classes and use instance variables such as @myname
+
+class Dog   
+	def set_name( aName )
+		@myname = aName
+	end
+	
+	def get_name
+		 return @myname
+	end
+	
+	def talk
+		return 'woof!'
+	end
+end
+
+
+class Cat  
+	def set_name( aName )
+		@myname = aName
+	end
+	
+	def get_name
+		 return @myname
+	end
+	
+	def talk
+		return 'miaow!'
+	end
+end
+
+# --- Create instances (objects) of the Dog and Cat classes
+mydog = Dog.new
+yourdog = Dog.new
+mycat = Cat.new
+yourcat = Cat.new
+someotherdog = Dog.new
+
+# --- Name them
+mydog.set_name( 'Fido' )
+yourdog.set_name( 'Bonzo' )
+mycat.set_name( 'Tiddles' )
+yourcat.set_name( 'Flossy' )
+
+
+# --- Get their names and display them
+# Dogs
+puts(mydog.get_name)
+puts(yourdog.get_name)
+# hmmm, but what happens here if the dog has no name?
+puts(someotherdog.get_name)
+# Cats
+puts(mycat.get_name)
+puts(yourcat.get_name)
+
+# --- Ask them to talk
+puts(mydog.talk)
+puts(yourdog.talk)
+puts(mycat.talk)
+puts(yourcat.talk)

ch1/6dogs.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+# define a class and create some objects
+
+
+class Thing
+		def set_name( aName )
+			@name = aName
+		end
+		
+		def get_name
+			return @name
+		end
+end
+
+class Treasure
+      def initialize( aName, aDescription )
+        @name         = aName
+        @description  = aDescription
+      end
+      
+      def to_s # override default to_s method
+           "The #{@name} Treasure is #{@description}\n"
+      end
+end
+
+thing1 = Thing.new
+thing1.set_name( "A lovely Thing" )
+puts thing1.get_name
+
+t1 = Treasure.new("Sword", "an Elvish weapon forged of gold")
+t2 = Treasure.new("Ring", "a magic ring of great power")
+puts t1.to_s
+puts t2.to_s
+# The inspect method lets you look inside an object
+puts "Inspecting 1st treasure: #{t1.inspect}"

ch1/7treasure.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+# Show string representations of various objects
+# using the to_s method
+
+class Treasure
+      def initialize( aName, aDescription )
+        @name         = aName
+        @description  = aDescription
+      end
+# This time we won't override to_s so the Treasure object
+# will use the default to_s method...
+end
+
+
+t = Treasure.new( "Sword", "A lovely Elvish weapon" )
+puts("   Class.to_s")
+puts(Class.to_s)
+puts("   Object.to_s")
+puts(Object.to_s)
+puts("   String.to_s")
+puts(String.to_s)
+puts("   100.to_s")
+puts(100.to_s)
+puts("   Treasure.to_s")
+puts(Treasure.to_s)
+puts("   t.to_s")
+puts(t.to_s) 
+puts("   t.inspect")
+puts(t.inspect)

ch1/8to_s.rb

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+# this is a comment
+
+puts( "hello" ) # this is also a comment
+
+=begin
+ This is a 
+ multiline
+ comment
+=end
+
+puts( "goodbye" )

ch1/comments.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+
+class Treasure
+      def initialize( aName, aDescription )
+        @name         = aName
+        @description  = aDescription
+      end
+      
+      def to_s # override default to_s method
+           "The #{@name} Treasure is #{@description}\n"
+      end
+end
+
+
+a = "hello"
+b = 123
+c = Treasure.new( "ring", "a glittery gold thing" )
+
+p( a )
+p( b )
+p( c )

ch1/p.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+
+localvar = "hello"
+$globalvar = "goodbye" 
+
+def amethod
+	localvar = 10
+	puts( localvar )
+	puts( $globalvar )
+end
+
+def anotherMethod
+	localvar = 500
+	$globalvar = "bonjour"
+	puts( localvar )
+	puts( $globalvar )
+end
+
+
+amethod
+puts
+anotherMethod
+puts
+amethod
+puts
+puts( localvar )
+puts( $globalvar )

ch1/variables.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+
+puts('Block #1')
+3.times do |i|
+    puts( i )
+end
+
+puts('Block #2')
+3.times { |i|
+    puts( i )
+}
+
+# Here's an example that avoids using a block
+def aMethod( i )
+	puts( i )
+end
+
+puts('Method Call')
+for i in 0..2
+	aMethod( i )
+end

ch10/1blocks.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+
+puts('Block #3' )
+b3 = [1,2,3].collect{|x| x*2}    
+puts( b3.inspect )
+
+puts('Block #4' )
+b4 = ["hello","good day","how do you do"].collect{|x| x.capitalize }
+puts( b4.inspect )
+
+puts('Block #5' )
+b5 = ["hello","good day","how do you do"].each{|x| x.capitalize }      
+puts(b5.inspect)
+
+puts('Block #6' )
+b6 = ["hello","good day","how do you do"].each{|x| x.capitalize! }      
+puts(b6.inspect)
+
+puts('---Block #7---' )
+newstr = ''
+a = "hello world".split(//).each{ |x| newstr << x.capitalize
+	puts(newstr) 
+}
+puts("a.inspect=#{a.inspect}")
+puts("newsstr='#{newstr}'")
+
+puts('---Block #8---' )
+newstr = ''
+a = "hello world".each_byte{|x| newstr << (x.chr).capitalize
+	puts(newstr) 
+}
+puts("a.inspect=#{a.inspect}")
+puts("newsstr='#{newstr}'")

ch10/2blocks.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+
+puts( '--- Proc.new ---' )
+a = Proc.new{|x| x = x*10; puts(x) }
+a.call(100)
+
+puts('----Block #1---' )
+b = lambda{|x| x = x*10; puts(x) }
+b.call(100)
+
+puts('---Block #2---' )
+c = proc{|x| x.capitalize! }      
+c1 = c.call( "hello" )
+puts( c1 )
+
+puts('---Block #3---' )
+d = lambda{|x| x.capitalize! }      
+d1 = ["hello","good day","how do you do"].each{ |s| d.call(s)}
+puts(d1.inspect)

ch10/3blocks.rb

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+# The Book of Ruby - http://www.sapphiresteel.com
+
+# using 'yield' to execute a block
+
+def aMethod
+	puts('--- In aMethod ---' )
+	yield
+end
+
+aMethod{ puts( "Good morning" ) }
+
+
+def caps( anarg ) 
+	puts('--- In caps method ---' )
+	yield( anarg )
+end
+
+caps( "a lowercase string" ){ |x| x.capitalize! ; puts( x ) }
+
+puts( "And now a block within a block..." )
+# a block within a block
+["hello","good day","how do you do"].each{ 
+	|s| 
+	caps( s ){ |x| x.capitalize!
+		puts( x )
+	}  
+}
+
+