[ Arithmetic | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]
# //(+Number1, +Number2, -Result)

Evaluates the integer quotient Number1 // Number2 and unifies the resulting
value with Result.
*Number1*
- Integer.
*Number2*
- Integer.
*Result*
- A variable or integer.

## Description

This predicate is used by the ECLiPSe compiler to expand evaluable
arithmetic expressions. So the call to //(Number1, Number2, Result) is
equivalent to
Result is Number1 // Number2

which should be preferred for portability.
This division operates on integer arguments, and delivers an integer
result rounded towards zero (truncated). The corresponding remainder
is computed by the rem operation, such that the following equivalence
always holds:

X =:= (X rem Y) + (X // Y) * Y.

In coroutining mode, if Number1 or Number2 are uninstantiated, the call
to (//)/3 is delayed until these variables are instantiated.

### Modes and Determinism

### Exceptions

*(4) instantiation fault *
- Number1 or Number2 is not instantiated (non-coroutining mode only).
*(5) type error *
- Number1 or Number2 is a number but not an integer.
*(5) type error *
- Result is a number but not an integer.
*(24) number expected *
- Number1 or Number2 is not of a numeric type.
*(24) number expected *
- Result is neither a number nor a variable.
*(20) arithmetic exception *
- Illegal arithmetic operation: division by 0

## Examples

Success:
X is 10 // 3. ( gives X = 3)
//( 10, 3, 3).
//(-10, 3, -3).
//( 10, -3, -3).
//(-10, -3, 3).
Fail:
//(1, 2, 3).
Error:
//(A, 2, 6). (Error 4).
//(5, 2, r). (Error 5).
//(6, 2.0, 3.0). (Error 5).
//(2, 0, Result). (Error 20).
//(4 + 2, 2, 12). (Error 24).

## See Also

is / 2, div / 3, rem / 3