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. What's RVM, Gem, Rake, Bundler, RDoc, ri, irb?

  1. Unicode 💎
  2. Quote String
  3. Quote Long String
  4. Format String
  5. String Operations
  6. True, False
  7. “if then else”
  8. for, while, Loop
  9. List
  10. Loop Thru List
  11. Hash Table
  12. Function Optional Parameter
  13. Map f to List
  14. Complex Numbers
  1. Intro to Reading Ruby Doc: What's M, C, ::, # ?
  2. Predefined Global Variables