Short-circuit evaluation

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Short-circuit evaluation, minimal evaluation, or McCarthy evaluation (after John McCarthy) is the semantics of some Boolean operators in some programming languages in which the second argument is executed or evaluated only if the first argument does not suffice to determine the value of the expression: when the first argument of the AND function evaluates to false, the overall value must be false; and when the first argument of the OR function evaluates to true, the overall value must be true. In programming languages with lazy evaluation (Lisp, Perl, Haskell), the usual Boolean operators short-circuit. In others (Ada, Java, Delphi), both short-circuit and standard Boolean operators are available. For some Boolean operations, like exclusive or (XOR), it is impossible to short-circuit, because both operands are needed to determine a result. Short-circuit operators are, in effect, control structures rather than simple arithmetic operators, as they are not strict. In imperative language terms...

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