15.16.3

Remainder Operator

%

EXPRESSIONS

Examples:

5%3

produces

 2

(note that

 5/3

produces

 1

)

5%( 3)

produces

 2

(note that

 5/( 3)

produces

  1

)

( 5)%3

produces

  2

(note that

 ( 5)/3

produces

  1

)

( 5)%( 3)

produces

  2

(note that

 ( 5)/( 3)

produces

 1

)

The result of a floating point remainder operation as computed by the

%

 oper 

ator is

not

 the same as that produced by the remainder operation defined by IEEE

754. The IEEE 754 remainder operation computes the remainder from a rounding

division, not a truncating division, and so its behavior is

not

 analogous to that of

the usual integer remainder operator. Instead, the Java language defines

%

 on float 

ing point operations to behave in a manner analogous to that of the Java integer

remainder operator; this may be compared with the C library function

fmod

. The

IEEE 754 remainder operation may be computed by the Java library routine

Math.IEEEremainder

 ( 20.11.14).

The result of a Java floating point remainder operation is determined by the

rules of IEEE arithmetic:

If either operand is NaN, the result is NaN.

If the result is not NaN, the sign of the result equals the sign of the dividend.

If the dividend is an infinity, or the divisor is a zero, or both, the result is NaN.

If the dividend is finite and the divisor is an infinity, the result equals the divi 

dend.

If the dividend is a zero and the divisor is finite, the result equals the dividend.

In the remaining cases, where neither an infinity, nor a zero, nor NaN is

involved, the floating point remainder

r

 from the division of a dividend

n

 by a

divisor

d

 is defined by the mathematical relation

r

=

n

(

d

q

)

 where

q

 is an

integer that is negative only if

n

d

 is negative and positive only if

n

d

 is

positive, and whose magnitude is as large as possible without exceeding the

magnitude of the true mathematical quotient of

n

 and

d

.

Evaluation of a floating point remainder operator

%

 never throws a run time

exception, even if the right hand operand is zero. Overflow, underflow, or loss of

precision cannot occur.

Examples:

5.0%3.0

produces

 2.0

5.0%( 3.0)

produces

 2.0

( 5.0)%3.0

produces

  2.0

( 5.0)%( 3.0)

produces

  2.0

354