# BITNOT

Sets the specified bit in a bitstring to its opposite value.

## Synopsis

```BITNOT(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 its opposite value. 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 error.

## Description

The BITNOT function defines a bit string using bitstring and changes (flips) 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 0, BITNOT sets it to 1. If the bit specified by bitno has a value of 1, BITNOT sets it to 0.

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 BITNOT function always changes the specified bit. The BITSET function only sets the specified bit if its value is 0. The BITRESET function only sets the specified bit if its value is 1.

## Examples

The following example specifies a bitstring of 64 (binary 1000000), and bitno sets bit position 0 to its opposite. This results in the binary string 1000001, the integer value of which is 65:

`PRINT BITNOT(64,0);  ! Returns 65`

The following example specifies a bitstring of 64 (binary 1000000), and bitno sets bit position 4 to its opposite. This results in the binary string 1010000, the integer value of which is 80:

`PRINT BITNOT(64,4);  ! Returns 80`

The following example specifies a bitstring of 65 (binary 1000001), and bitno specifies setting bit position 0 to its opposite. This results in the binary string 1000000, the integer value of which is 64:

`PRINT BITNOT(65,0);  ! Returns 64`

The following example specifies a bitstring of 8 (binary 1000), and bitno specifies setting bit position 4 to its opposite. The bitstring has an implicit bit position of 4 with a value of 0. Setting this bit to 1 returns the binary string 11000, the integer value of which is 24:

`PRINT BITNOT(8,4);  ! Returns 24`

The following example specifies a bitstring of 1 (binary 1), and bitno sets bit position 0 to its opposite. This results in the binary string 0, the integer value of which is 0:

`PRINT BITNOT(1,0);  ! Returns 0`