What do these operators do?

Question

Going through the "timeouts" example of the elapsedMillis library (https://github.com/pfeerick/elapsedMillis) I found the following statement:

digitalWrite(LEDPIN, flashPattern[ledIndex++] ? ledBrightness : !ledBrightness);

• flashpattern is an array of boolean variables (boolean flashPattern[] = { 1,1,1,1,1,1,1,0,1,1,0 };)
• ledBrightness is a boolean as well.

What does the "?" and the ":" do there? are these boolean operators?

Answer 1

A ? B : C;

is shorthand for

if(A) {
    B;
} else {
    C;
}

Answer 2

They are the conditional operator. If the expression before the ? is true then the result is the expression before the :, otherwise it is the expression after.