EXPRESSIONS

Multiplication Operator

*

15.16.1

15.16   Multiplicative Operators

The operators

*

,

/

, and

%

 are called the

multiplicative operators

. They have the

same precedence and are syntactically left associative (they group left to right).

MultiplicativeExpression:

UnaryExpression

MultiplicativeExpression

 *

UnaryExpression

MultiplicativeExpression

 /

UnaryExpression

MultiplicativeExpression

 %

UnaryExpression

The type of each of the operands of a multiplicative operator must be a primi 

tive numeric type, or a compile time error occurs. Binary numeric promotion is

performed on the operands ( 5.6.2). The type of a multiplicative expression is the

promoted type of its operands. If this promoted type is

int

 or

long

, then integer

arithmetic is performed; if this promoted type is

float

 or

double

, then floating 

point arithmetic is performed.

15.16.1   Multiplication Operator

*

Entia non sunt multiplicanda praeter necessitatem.

William of Occam (c. 1320)

The binary

*

 operator performs multiplication, producing the product of its oper 

ands. Multiplication is a commutative operation if the operand expressions have

no side effects. While integer multiplication is associative when the operands are

all of the same type, floating point multiplication is not associative.

If an integer multiplication overflows, then the result is the low order bits of

the mathematical product as represented in some sufficiently large two's comple 

ment format. As a result, if overflow occurs, then the sign of the result may not be

the same as the sign of the mathematical product of the two operand values.

The result of a floating point multiplication is governed by the rules of IEEE

754 arithmetic:

If either operand is NaN, the result is NaN.

If the result is not NaN, the sign of the result is positive if both operands have

the same sign, and negative if the operands have different signs.

Multiplication of an infinity by a zero results in NaN.

Multiplication of an infinity by a finite value results in a signed infinity. The

sign is determined by the rule stated above.

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