TECH603 Day 1 Example - "Truthy" and "Falsey"

true_false.rb

# output the values
puts true
puts false

# test true
if true then
  puts "true is true"
else
  puts "true is not true"
end

# test false
if false
  puts "false is not false"
else
  puts "false is false"
end

# test not false
if !false
  puts "the condition is not false"
else
  puts "the condition is false"
end

# test equal
if 1 == 1
  puts "one equals one"
else
  puts "one does not equal one"
end

# test not equal
if 1 == 2
  puts "one equals two"
else
  puts "one does not equal two"
end

# test string equality
if "one" == "one"
  puts "one equals one"
else
  puts "one does not equal one"
end

# test result of comparison
if 1 < 2
  puts "one less than two"
else
  puts "one NOT less than two"
end

# test zero
if 0
  puts "0 is true"
else
  puts "0 is false"
end

# test one
if 1
  puts "1 is true"
else
  puts "1 is false"
end

# test string
if "thing"
  puts "string thing is true"
else
  puts "string thing is false"
end

# test nil
if nil
  puts "nil is true"
else
  puts "nil is false"
end

# test empty string
if ""
  puts "empty string is true"
else
  puts "empty string is false"
end

# test regular expression match
if "string" =~ /ring/
  puts "string string contains ring"
else
  puts "string string does not contain ring"
end

# test regular expression non-match
if "string" =~ /grin/
  puts "string string contains grin"
else
  puts "string string does not contain grin"
end

# test empty array
if []
  puts "empty array is true"
else
  puts "empty array is false"
end

# test match with in-line assignment
if position = ("string" =~ /ring/)
  puts "position is #{position}"
else
  puts "no position found"
end

puts "position is still #{position}"

# test with assignment of the return value from the conditional
message = if true
  "true message"
else
  "false message"
end

# output the message
puts message