How can "A0, D7" etc be integers?

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Thanks @peekay123! That makes perfect sense. Also explains another doubt i had elsewhere.

Since i don’t want to start another topic just for this Q, could you tell me what exactly this command does?

int pinNumber = (command.charAt(1) - '0') - 1;

…i understand command.charAt(1), but what is the - 0 and -1 for? (This if from the “Controlling LEDs over the 'net” example)

Thanks,
R