[ Arithmetic | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]

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

Result is Number with the Index'th bit set.

Number
  Integer.
Index
  Non-negative integer.
Result
  A variable or integer.

## Description

Set the Index'th bit in Number giving Result. The least significant bit has index zero. Two's complement representation is assumed. This predicate is used by the ECLiPSe compiler to expand evaluable arithmetic expressions. So the call to setbit(Number, Index, Result) is equivalent to

        Result is setbit(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

- setbit(+, +, -) is det

### Exceptions

(4) instantiation fault
  Number or Index is not instantiated (non-coroutining mode only).
(5) type error
  Result is a number but not an integer.
(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.
(24) number expected
  Result is neither a number nor a variable.

## Examples

    Success:
          setbit(0, 3, 8).
          setbit(1, 8, X).             gives X=257.
          X is setbit(setbit(0,3),5).  gives X=40.

## See Also

is / 2, clrbit / 3, getbit / 3