bit strings functions This section describes functions and operators for examining and manipulating bit strings, that is values of the types bit and bit varying. (While only type bit is mentioned in these tables, values of type bit varying can be used interchangeably.) Bit strings support the usual comparison operators shown in , as well as the operators shown in . Operator Description Example(s) bit || bit bit Concatenation B'10001' || B'011' 10001011 bit & bit bit Bitwise AND (inputs must be of equal length) B'10001' & B'01101' 00001 bit | bit bit Bitwise OR (inputs must be of equal length) B'10001' | B'01101' 11101 bit # bit bit Bitwise exclusive OR (inputs must be of equal length) B'10001' # B'01101' 11100 ~ bit bit Bitwise NOT ~ B'10001' 01110 bit << integer bit Bitwise shift left (string length is preserved) B'10001' << 3 01000 bit >> integer bit Bitwise shift right (string length is preserved) B'10001' >> 2 00100 Some of the functions available for binary strings are also available for bit strings, as shown in . Function Description Example(s) bit_count bit_count ( bit ) bigint Returns the number of bits set in the bit string (also known as popcount). bit_count(B'10111') 4 bit_length bit_length ( bit ) integer Returns number of bits in the bit string. bit_length(B'10111') 5 length bit string length length ( bit ) integer Returns number of bits in the bit string. length(B'10111') 5 octet_length octet_length ( bit ) integer Returns number of bytes in the bit string. octet_length(B'1011111011') 2 overlay overlay ( bits bit PLACING newsubstring bit FROM start integer FOR count integer ) bit Replaces the substring of bits that starts at the start'th bit and extends for count bits with newsubstring. If count is omitted, it defaults to the length of newsubstring. overlay(B'01010101010101010' placing B'11111' from 2 for 3) 0111110101010101010 position position ( substring bit IN bits bit ) integer Returns first starting index of the specified substring within bits, or zero if it's not present. position(B'010' in B'000001101011') 8 substring substring ( bits bit FROM start integer FOR count integer ) bit Extracts the substring of bits starting at the start'th bit if that is specified, and stopping after count bits if that is specified. Provide at least one of start and count. substring(B'110010111111' from 3 for 2) 00 get_bit get_bit ( bits bit, n integer ) integer Extracts n'th bit from bit string; the first (leftmost) bit is bit 0. get_bit(B'101010101010101010', 6) 1 set_bit set_bit ( bits bit, n integer, newvalue integer ) bit Sets n'th bit in bit string to newvalue; the first (leftmost) bit is bit 0. set_bit(B'101010101010101010', 6, 0) 101010001010101010 In addition, it is possible to cast integral values to and from type bit. Casting an integer to bit(n) copies the rightmost n bits. Casting an integer to a bit string width wider than the integer itself will sign-extend on the left. Some examples: 44::bit(10) 0000101100 44::bit(3) 100 cast(-44 as bit(12)) 111111010100 '1110'::bit(4)::integer 14 Note that casting to just bit means casting to bit(1), and so will deliver only the least significant bit of the integer.