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### B.1.3 Bits

Bit manipulation functions.

Note that for bitwise AND, OR, XOR of integer values etc you can use the java bitwise operators "`&`", "`|`", "`^`".

`hasBit( value, bitIndex )`
  Determines whether a given integer has a certain bit set to 1.

  - Parameters:
    - `value` (long integer): integer whose bits are to be tested
    - `bitIndex` (integer): index of bit to be tested in range 0..63, where 0 is the least significant bit
  - Return value
    - (boolean): true if bit is set; more or less equivalent to `(value & 1L<<bitIndex) != 0`
  - Examples:
    - `hasBit(64, 6) = true`
    - `hasBit(63, 6) = false`
`bitCount( i )`
  Returns the number of set bits in the 64-bit two's complement representation of the integer argument.

  - Parameters:
    - `i` (long integer): integer value
  - Return value
    - (integer): number of "1" bits in the binary representation of `i`
  - Examples:
    - `bitCount(64) = 1`
    - `bitCount(3) = 2`
`toBinary( value )`
  Converts the integer argument to a binary string consisting only of 1s and 0s.

  - Parameters:
    - `value` (long integer): integer value
  - Return value
    - (String): binary representation of `value`
  - Examples:
    - `toBinary(42) = "101010"`
    - `toBinary(255^7) = "11111000"`
`fromBinary( binVal )`
  Converts a string representing a binary number to its integer value.

  - Parameters:
    - `binVal` (String): binary representation of value
  - Return value
    - (integer): integer value represented by binary string `binVal`
  - Example:
    - `fromBinary("101010") = 42`

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TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page: http://www.starlink.ac.uk/topcat/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk