Question

I need to have my integer counter have values from 1 to 6 inclusive in wrap around fashion. Namely starting from 1, I count to 6 and go back to 1. I wonder if it’s possible to achieve using some sort of bitwise logic. Of course it’s trivial with if statement as below but I am wondering about one liner 🙂

int counter = 1;

for...
    do something
    if (counter++ == 7) counter = 1;

Addition:
Here is why I want 1 liner:

byte output = (byte)((inputByte & 0xF8) | counter++);

Answer 1

Use the modulo operator.

do something;    
++counter; counter %= 7; ++counter;

To use real bitwise operations your modulo must be a power-of-2 which is not the case here.

PS: If your counter started at 0 instead of 1, you wouldn’t need the second ++counter and would write something like :

for (int counter = 0; (somecondition); ++counter, counter %= 7)
{
    do something;
}

PPS: Note that generally an if performs faster than a modulo, tho.