15.24

Conditional Operator

? :

EXPRESSIONS

The type of a conditional expression is determined as follows:

If the second and third operands have the same type (which may be the null

type), then that is the type of the conditional expression.

Otherwise, if the second and third operands have numeric type, then there are

several cases:

N

If one of the operands is of type

byte

 and the other is of type

short

, then

the type of the conditional expression is

short

.

N

If one of the operands is of type

T

 where

T

 is

byte

,

short

, or

char

, and the

other operand is a constant expression of type

int

 whose value is represent 

able in type

T

, then the type of the conditional expression is

T

.

N

Otherwise, binary numeric promotion ( 5.6.2) is applied to the operand

types, and the type of the conditional expression is the promoted type of the

second and third operands.

If one of the second and third operands is of the null type and the type of the

other is a reference type, then the type of the conditional expression is that

reference type.

If the second and third operands are of different reference types, then it must

be possible to convert one of the types to the other type (call this latter type

T

)

by assignment conversion ( 5.2); the type of the conditional expression is

T

.

It is a compile time error if neither type is assignment compatible with the

other type.

At run time, the first operand expression of the conditional expression is eval 

uated first; its

boolean

 value is then used to choose either the second or the third

operand expression:

If the value of the first operand is

true

, then the second operand expression is

chosen.

If the value of the first operand is

false

, then the third operand expression is

chosen.

The chosen operand expression is then evaluated and the resulting value is con 

verted to the type of the conditional expression as determined by the rules stated

above. The operand expression not chosen is not evaluated for that particular eval 

uation of the conditional expression.

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