The conditional-or operator
|| operator is like
| (§15.22.2), but evaluates its right-hand operand only if the value of its left-hand operand is
ConditionalOrExpression: ConditionalAndExpression ConditionalOrExpression
The conditional-or operator is syntactically left-associative (it groups left-to-right).
The conditional-or operator is fully associative with respect to both side effects and result value. That is, for any expressions a, b, and c, evaluation of the expression
((a) || (b)) || (c) produces the same result, with the same side effects occurring in the same order, as evaluation of the expression
(a) || ((b) || (c)).
Each operand of the conditional-or operator ...