02_numbers_and_strings.rb

# Programming exercise 5.2: Numbers and Strings
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# Tutorial Numbers: http://ruby-for-beginners.rubymonstas.org/built_in_classes/numbers.html #
# Tutorial Strings: http://ruby-for-beginners.rubymonstas.org/built_in_classes/strings.html #
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# In ruby, numbers are objects like everything else
puts "Is '5' an object?"
puts 5.is_a?(Object)
puts # ------------ print empty line -------------

# Like any other object, numbers have methods
puts "Is 5.zero?"
puts 5.zero?
puts "Is 0.zero?"
puts 0.zero?
puts # ------------ print empty line -------------

# So we can add two numbers and remember the result with the variable 'expression1'
expression1 = 2 + 5
puts "The result of the expression 2 + 5 is:"
puts expression1

# But if we add two numbers in double quotes
expression2 = "2" + "5"
# Oh, and by the way, we can write the literal quotation mark inside a string
# with a so called 'escape character' the backslash \ so the quotation marks
# don't terminate the string
puts "The result of the expression \"2\" + \"5\" is:"
puts expression2
# TODO: So as you have seen in your command line, the result is '25'
# TODO: Can you explain why?
puts "Why?"
puts # ------------ print empty line -------------


# Does this help?
puts "If we call \"5\".class, we get"
puts "5".class

# Does this help?
puts "If we call 5.class, we get"
puts 5.class
puts # ------------ print empty line -------------

# TODO: We want to output a quote of Sepp Herberger here
puts "Attention: We will get an error message now:"
puts "\"No implicit conversion of Fixnum into String (TypeError)\" "
puts # ------------ print empty line -------------
puts "Sepp Herberger: \"Das Spiel dauert " + 90 + " Minuten.\""
# TODO: How can you fix that??