C# supports two floating point types: float
and double
. The float
and double
types are represented using the 32-bit single-precision and 64-bit double-precision IEEE 754 formats, which provide the following sets of values:
1.0
/
0.0
yields positive infinity, and –1.0
/
0.0
yields negative infinity.float
, 0 < m < 224 and -149 = e = 104, and for double
, 0 < m < 253 and -1075 = e = 970.The float
type can represent values ranging from approximately 1.5 × 10-45 to 3.4 × 1038 with a precision of 7 digits.
The double
type can represent values ranging from approximately 5.0 × 10-324 to 1.7 × 10308 with a precision of 15-16 digits.
If one of the operands of a binary operator is of a floating-point type, then the other operand must be of an integral type or a floating-point type, and the operation is evaluated as follows:
double
, the other operand is converted to double
, the operation is performed using at least double
range and precision, and the type of the result is double
(or bool
for the relational operators).float
range and precision, and the type of the result is float
(or bool
for the relational operators).The floating-point operators, including the assignment operators, never produce exceptions. Instead, in exceptional situations, floating-point operations produce zero, infinity, or NaN, as described below:
Floating-point operations may be performed with higher precision than the result type of the operation. For example, some hardware architectures support an "extended" or "long double" floating-point type with greater range and precision than the double
type, and implicitly perform all floating-point operations using this higher precision type. Only at excessive cost in performance can such hardware architectures be made to perform floating-point operations with less precision, and rather than require an implementation to forfeit both performance and precision, C# allows a higher precision type to be used for all floating-point operations. Other than delivering more precise results, this rarely has any measurable effects. However, in expressions of the form x
*
y
/
z
, where the multiplication produces a result that is outside the double
range, but the subsequent division brings the temporary result back into the double
range, the fact that the expression is evaluated in a higher range format may cause a finite result to be produced instead of an infinity.