(a && b) versus (a and b)

Given :

a=true
b=false

why can I开发者_JS百科 do :

puts [a && b, a || b]  #[false, true]

but not

puts [a and b, a or b] 

syntax error, unexpected keyword_and, expecting ']' puts [a and b, a or b]

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Apparently, the operator precedence for the comma is higher than "and" but lower than &&.

Putting parenthesis around the elements works:

[(a and b), (a or b)]

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you need to simply group the terms to avoid precedence issues:

puts [(a and b),(a or b)]