Floating-point numeric types (C# reference)

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The floating-point types are a subset of the simple types and can be initialized with literals. All floating-point types are also value types. All floating-point numeric types support arithmetic, comparison, and equality operators.

Characteristics of the floating-point types

C# supports the following predefined floating-point types:

C# type/keyword Approximate range Precision .NET type
float ±1.5 x 10−45 to ±3.4 x 1038 ~6-9 digits System.Single
double ±5.0 × 10−324 to ±1.7 × 10308 ~15-17 digits System.Double
decimal ±1.0 x 10-28 to ±7.9228 x 1028 28-29 digits System.Decimal

In the preceding table, each C# type keyword from the leftmost column is an alias for the corresponding .NET type. They are interchangeable. For example, the following declarations declare variables of the same type:

double a = 12.3;
System.Double b = 12.3;

The default value of each floating-point type is zero, 0. Each of the floating-point types has the MinValue and MaxValue constants that provide the minimum and maximum finite value of that type. The float and double types also provide constants that represent not-a-number and infinity values. For example, the double type provides the following constants: Double.NaN, Double.NegativeInfinity, and Double.PositiveInfinity.

Because the decimal type has more precision and a smaller range than both float and double, it's appropriate for financial and monetary calculations.

You can mix integral types and floating-point types in an expression. In this case, the integral types are converted to floating-point types. The evaluation of the expression is performed according to the following rules:

  • If one of the floating-point types is double, the expression evaluates to double, or to bool in relational comparisons or comparisons for equality.
  • If there is no double type in the expression, the expression evaluates to float, or to bool in relational comparisons or comparisons for equality.

A floating-point expression can contain the following sets of values:

  • Positive and negative zero
  • Positive and negative infinity
  • Not-a-Number value (NaN)
  • The finite set of nonzero values

For more information about these values, see IEEE Standard for Binary Floating-Point Arithmetic, available on the IEEE website.

You can use either standard numeric format strings or custom numeric format strings to format a floating-point value.

Floating-point literals

By default, a floating-point numeric literal on the right side of the assignment operator is treated as double. You can use suffixes to convert a floating-point or integral literal to a specific type:

  • The d or D suffix converts a literal to a double.
  • The f or F suffix converts a literal to a float.
  • The m or M suffix converts a literal to a decimal.

The following examples show each suffix:

double d = 3D;
d = 4d;
float f = 3.5F;
f = 5.4f;
decimal myMoney = 300.5m;
myMoney = 400.75M;

Conversions

There's an implicit conversion (called a widening conversion) from float to double because the range of float values is a proper subset of double and there is no loss of precision from float to double.

You must use an explicit cast to convert one floating-point type to another floating-point type when an implicit conversion isn't defined from the source type to the destination type. This is called a narrowing conversion. The explicit case is required because the conversion can result in data loss. There's no implicit conversion between other floating-point types and the decimal type because the decimal type has greater precision than either float or double.

For more information about implicit numeric conversions, see Implicit Numeric Conversions Table.

For more information about explicit numeric conversions, see Explicit Numeric Conversions Table.

See also