[ Arithmetic | Reference Manual | Alphabetic Index ]
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
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