Intro to Reading Ruby Doc: What's M, C, ::, # ?

By Xah Lee. Date:

This page is a guide to reading Ruby's official doc, for Ruby beginners.

Ruby Doc home page is at

On top, you can see {Core, Std-lib, Gems}. These are most important.

For beginner, you'd be concerned with the Core and Std-lib.

Now, look at the Ruby Core doc page: The left side are classes. The right side are methods.

ruby doc screenshot 2013-01-01 screenshot

On the left side, the classes, some have a gray “C” some have “M”.

This means, for beginner, you can probably ignore all those M ones.

On the right side, are methods, with :: or #.

If you have a question, put $5 at patreon and message me.

  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. 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?