14.2.6.2 Binary numeric promotions

王朝other·作者佚名  2006-01-10
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This clause is informative.

Binary numeric promotion occurs for the operands of the predefined +, ?, *,

/, %, &, |, ^, ==, !=, >, <, >=,

and <= binary operators. Binary numeric promotion implicitly converts both

operands to a common type

which, in case of the non-relational operators, also becomes the result

type of the operation. Binary numeric

promotion consists of applying the following rules, in the order they

appear here:

?If either operand is of type decimal, the other operand is converted to

type decimal, or a compiletime

error occurs if the other operand is of type float or double.

?Otherwise, if either operand is of type double, the other operand is

converted to type double.

?Otherwise, if either operand is of type float, the other operand is

converted to type float.

?Otherwise, if either operand is of type ulong, the other operand is

converted to type ulong, or a

compile-time error occurs if the other operand is of type sbyte, short,

int, or long.

?Otherwise, if either operand is of type long, the other operand is

converted to type long.

?Otherwise, if either operand is of type uint and the other operand is of

type sbyte, short, or int,

both operands are converted to type long.

?Otherwise, if either operand is of type uint, the other operand is

converted to type uint.

?Otherwise, both operands are converted to type int.

[Note: The first rule disallows any operations that mix the decimal type

with the double and float types.

The rule follows from the fact that there are no implicit conversions

between the decimal type and the

double and float types. end note]

[Note: Also note that it is not possible for an operand to be of type ulong

when the other operand is of a

signed integral type. The reason is that no integral type exists that can

represent the full range of ulong as

well as the signed integral types. end note]

In both of the above cases, a cast expression can be used to explicitly

convert one operand to a type that is

compatible with the other operand.

[Example: In the example

decimal AddPercent(decimal x, double percent) {

return x * (1.0 + percent / 100.0);

}

a compile-time error occurs because a decimal cannot be multiplied by a

double. The error is resolved by

explicitly converting the second operand to decimal, as follows:

decimal AddPercent(decimal x, double percent) {

return x * (decimal)(1.0 + percent / 100.0);

}

end example]

End of informative text.

 
 
 
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