bitpos

BITPOS

BITPOS key bit [start] [end]

Return the position of the first bit set to 1 or 0 in a string.

The position is returned, thinking of the string as an array of bits from left to right, where the first byte's most significant bit is at position 0, the second byte's most significant bit is at position 8, and so forth.

The same bit position convention is followed by GETBIT and SETBIT.

By default, all the bytes contained in the string are examined. It is possible to look for bits only in a specified interval passing the additional arguments start and end (it is possible to just pass start, the operation will assume that the end is the last byte of the string. However there are semantic differences as explained later).