user24310: I dont know what meaning of this symbol - %.
for example,
buttonPressCount % numberOfLED == i
I hope anyone can tell me the name and basic function of this symbol.

user368: It is called the modulus operator, and it performs the modulo operation.
TL;CBR: It results in the remainder after division is performed.

24310: <p>I dont know what meaning of this symbol - %.</p>

<p>for example,</p>

<p>buttonPressCount % numberOfLED == i</p>

<p>I hope anyone can tell me the name and basic function of this symbol.</p>
 368: <p>It is called the modulus operator, and it performs the <a href="https://en.wikipedia.org/wiki/Modulo_operation" rel="nofollow noreferrer">modulo operation</a>.</p>

<p>TL;CBR: It results in the remainder after division is performed.</p>
