To be fair, digitalRead can take a variable as an argument, which variable should be a pin number that digitalRead will, well, read.
But if the result is not stored or used in an expression somehow, it is simply amounts to doing nothing at all.
Except if digitalRead misbehaves when asked to check a pin value that is nonsense, like 255, dunno what it does or doesn’t do in that case.
@tijn1987 srsly, look at the documentation for digitalRead without delay. I mean do it now.
a7