# FAQ: Arrays: Lesson - Length of Array Using sizeof()

This community-built FAQ covers the “Length of Array Using sizeof()” exercise from the lesson “Arrays: Lesson”.

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## FAQs on the exercise Length of Array Using sizeof()

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Hello,
I have a question regarding the following statement in this lesson:

for(int i = 0; i < sizeof(arr)/sizeof(int); i++) {

}

Is it efficient from performance point of view versus the static value (like “i < len”)?
Another word, does the “for” loop run the calculation of this part of conditional expression (“sizeof(arr)/sizeof(int)”) each cycle?

1 Like

That s a great question, I would be happy to know the answer too.
My guess is yes since it is a condition, there’s an evaluation each cycle.
If a C master could confirm or not?