crypto_denis/td_tp/tp1/aide.md

Setting a bit

Use the bitwise OR operator (|) to set a bit.

number |= 1 << x;

That will set bit x.

Clearing a bit

Use the bitwise AND operator (&) to clear a bit.

number &= ~(1 << x);

That will clear bit x. You must invert the bit string with the bitwise NOT operator (~), then AND it.

Toggling a bit

The XOR operator (^) can be used to toggle a bit.

number ^= 1 << x;

That will toggle bit x.

Checking a bit

You didn't ask for this but I might as well add it.

To check a bit, shift the number x to the right, then bitwise AND it:

bit = (number >> x) & 1;

That will put the value of bit x into the variable bit.

Changing the nth bit to x

Setting the nth bit to either 1 or 0 can be achieved with the following:

number ^= (-x ^ number) & (1 << n);

Bit n will be set if x is 1, and cleared if x is 0.