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iOS

Posted by Anthia Tillbury
Anthia Tillbury
3,388 Points

Both the AND and OR operators use short circuit evaluation?

*** SPOILER ALERT ***

One of the questions asked at the end of the "Collections and Control Flow" module (Swift) presses the issue of what "short circuit evaluation" means for the operators && and ||, but in the video explanation ("Logical Operators") I come away with a feeling that while Swift will "short circuit" an || operator (in that one of e.g. two conditions, can be met as a minimum), Swift will have to make sure that all conditions of an && statement are met.

So why then is the answer: not "False" as && cannot be short circuited? Is it because if one of the conditions is not met then it will automatically nullify the operator's function?

1 Answer

Jennifer Nordell
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STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

It's because if it starts going down the conditions to be met and hits a "False", it doesn't need to evaluate anything else. It's done :smiley: Since all conditions must evaluate to True for the entire expression to equal true. The OR is about the same, but in reverse. The first time it hits a True, it's done. Hope this helps! :sparkles:

edited for clarification

So yes, they both short circuit. OR short circuits on a True. AND short circuits on a False.

Didi Medina
Didi Medina
5,468 Points

Thanks for the explanation. Took me a second to wrap my head around it but makes complete sense.