Caché MultiValue Basic Reference
BITRESET
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Sets the specified bit in a bitstring to 0.
Synopsis
BITRESET(bitstring,bitno)
Arguments
bitstring The bit string, specified as an expression that resolves to a positive integer. For example, the integer 64 specifies the bitstring 1000000. The maximum bitstring value is 9223372036854775807.
bitno The bit position in bitstring to set to 0. An expression that resolves to a positive integer. Bit positions are counted right to left, beginning with position 0. The maximum bitno value is 62. A fractional bitno is truncated to its integer portion. A negative bitno generates a <FUNCTION> error.
Description
The BITRESET function defines a bit string using bitstring and resets to 0 one bit of that bit string at the location specified by bitno. Both values are specified as positive integers. If the bit specified by bitno has a value of 1, BITRESET sets it to 0. If the bit specified by bitno already has a value of 0, BITRESET leaves it unchanged.
Both bitstring and bitno can be expressed as either numbers or as strings. These numbers are converted to canonical form, with leading plus signs and leading and trailing zeros omitted. If either argument evaluates to the null string or a non-numeric string it is assumed to have a value of 0. A string is parsed as a number until a non-numeric character is encountered. Thus “7dwarves” is parsed as 7.
The BITRESET function sets a specified bit to 0. The BITSET function sets a specified bit to 1. The BITNOT function sets a specified bit to its opposite value.
Examples
The following example specifies a bitstring of 65 (binary 1000001), and bitno resets bit position 0 to the bit value 0. This results in the binary string 1000000, the integer value of which is 64:
PRINT BITRESET(65,0);  ! Returns 64
The following example specifies a bitstring of 64 (binary 1000000), and bitno resets bit position 6 to the bit value 0. This results in the binary string 0000000, the integer value of which is 0:
PRINT BITRESET(64,6);  ! Returns 0
The following example specifies a bitstring of 64 (binary 1000000), and bitno specifies resetting bit position 0 to the bit value 0. But because bit position 0 already has a bit value of 0, the binary string 1000000 (integer value 64) is returned unchanged:
PRINT BITRESET(64,0);  ! Returns 64
The following example specifies a bitstring of 8 (binary 1000), and bitno specifies resetting bit position 4 to the bit value 0. The bitstring has an implicit bit position of 4, which already has a value of 0. Thus the original binary string 1000 (integer value 8) is returned unchanged:
PRINT BITRESET(8,4);  ! Returns 8
The following example specifies a bitstring of 0 (binary 0), and bitno sets bit position 0 to the bit value 0. This results in the binary string 0, the integer value of which is 0:
PRINT BITRESET(0,0);  ! Returns 0
See Also