Difference between “and” and && in Ruby?

Question

What is the difference between the && and and operators in Ruby?

Answer 1

|| and && bind with the precedence that you expect from boolean operators in programming languages (&& is very strong, || is slightly less strong).

and and or have lower precedence.

For example, unlike ||, or has lower precedence than =:

> a = false || true
 => true 
> a
 => true 
> a = false or true
 => true 
> a
 => false

Likewise, unlike &&, and also has lower precedence than =:

> a = true && false
 => false 
> a
 => false 
> a = true and false
 => false 
> a
 => true 

What's more, unlike && and ||, and and or bind with equal precedence:

> !puts(1) || !puts(2) && !puts(3)
1
 => true
> !puts(1) or !puts(2) and !puts(3)
1
3
 => true 
> !puts(1) or (!puts(2) and !puts(3))
1
 => true

The weakly-binding and and or may be useful for control-flow purposes: see http://devblog.avdi.org/2010/08/02/using-and-and-or-in-ruby/ .