Ruby: True, False

By Xah Lee. Date: . Last updated: .

true and false are builtin objects.

The following evaluates to false:

Everything else is true (including 0, 0.0, "0", "", []). (this is similar to emacs lisp. [see Emacs Lisp Basics])

# -*- coding: utf-8 -*-
# ruby

if false then p "yes" else p "no" end # "no"

if nil then p "yes" else p "no" end # "no"

if () then p "yes" else p "no" end # "no"
# Empty paren eval to nil, so false.
# -*- coding: utf-8 -*-
# ruby

if true then p "yes" else p "no" end # "yes"

if 0 then p "yes" else p "no" end # "yes"

if 0.0 then p "yes" else p "no" end # "yes"

if [] then p "yes" else p "no" end # "yes"

if {} then p "yes" else p "no" end # "yes"

if "" then p "yes" else p "no" end # "yes"

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  1. Ruby Basics
  2. Doc Lookup
  3. Print Version String
  4. Unicode 💎
  5. Quote String
  6. Quote Long String
  7. Format String
  8. String Operations
  9. True, False
  10. “if then else”
  11. for, while, Loop
  12. List
  13. Loop Thru List
  14. Hash Table
  15. Function Optional Parameter
  16. Map f to List
  17. Complex Numbers
  18. Intro to Reading Ruby Doc: What's M, C, ::, # ?
  19. Predefined Global Variables
  20. What's RVM, Gem, Rake, Bundler, RDoc, ri, irb?