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getbit(+Number, +Index, -Result)
Result is the Index'th bit of Number.
- Non-negative integer.
- Output: integer.
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
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
- (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.
% 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.
is / 2, clrbit / 3, setbit / 3