15.17.2

Additive Operators (

+

 and

) for Numeric Types

EXPRESSIONS

In the code, note the careful conditional generation of the singular  

bottle

when appropriate rather than the plural  

bottles

 ; note also how the string con 

catenation operator was used to break the long constant string:

"You take one down and pass it around:"

into two pieces to avoid an inconveniently long line in the source code.

15.17.2   Additive Operators (

+

 and

) for Numeric Types

The binary

+

 operator performs addition when applied to two operands of numeric

type, producing the sum of the operands. The binary

 operator performs subtrac 

tion, producing the difference of two numeric operands.

Binary numeric promotion is performed on the operands ( 5.6.2). The type of

an additive expression on numeric operands 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.

Addition is a commutative operation if the operand expressions have no side

effects. Integer addition is associative when the operands are all of the same type,

but floating point addition is not associative.

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

mathematical sum as represented in some sufficiently large two's complement

format. If overflow occurs, then the sign of the result is not the same as the sign of

the mathematical sum of the two operand values.

The result of a floating point addition is determined using the following rules

of IEEE arithmetic:

If either operand is NaN, the result is NaN.

The sum of two infinities of opposite sign is NaN.

The sum of two infinities of the same sign is the infinity of that sign.

The sum of an infinity and a finite value is equal to the infinite operand.

The sum of two zeros of opposite sign is positive zero.

The sum of two zeros of the same sign is the zero of that sign.

The sum of a zero and a nonzero finite value is equal to the nonzero operand.

The sum of two nonzero finite values of the same magnitude and opposite

sign is positive zero.

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

involved, and the operands have the same sign or have different magnitudes,

the sum is computed. If the magnitude of the sum is too large to represent, we

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