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# getbit(+Number, +Index, -Result)

Result is the Index'th bit of Number.

Number
  Integer.
Index
  Non-negative integer.
Result
  Output: integer.

## Description

Returns the Index'th bit of Number, assuming binary two's complement representation. The least significant bit has index zero. The result is either 0 or 1. This predicate is used by the ECLiPSe compiler to expand evaluable arithmetic expressions. So the call to getbit(Number, Index, Result) is equivalent to

        Result is getbit(Number, Index)

which should be preferred.

In coroutining mode, if Number or Index are uninstantiated, the call is delayed until these variables are instantiated.

### Modes and Determinism

- getbit(+, +, -) is det

### Exceptions

(4) instantiation fault
  Number or Index is not instantiated (non-coroutining mode only).
(5) type error
  Number or Index is a number but not an integer.
(24) number expected
  Number or Index is not of a numeric type.

## Examples

        % 10 is binary 1010
        Result is getbit(10, 3).		% gives Result = 1.
        Result is getbit(10, 2).		% gives Result = 0.
        Result is getbit(10, 99).		% gives Result = 0.

## See Also

is / 2, clrbit / 3, setbit / 3