It must be a typo. Function calls have the highest priority here, followed by logic NOT and logic OR. !didIMakeAMistake() || CIsWrongHere(); !didIMakeAMi

It must be a typo. Function calls have the highest priority here, followed by logic NOT and logic OR. !didIMakeAMistake() || CIsWrongHere(); !didIMakeAMistake() is evaluated first (or you can say didIMakeAMistake() is executed and evaluated first, then its result is inverted and checked), if it's true, evaluation is finished. If it's false, CIsWrongHere(); is evaluated. It is indeed equivalent to if (didIMakeAMistake()) /* !didIMakeAMistake() == false? */ CIsWrongHere(); Without the invertion.