# double (C# Reference)

The double keyword signifies a simple type that stores 64-bit floating-point values. The following table shows the precision and approximate range for the double type.

Type |
Approximate range |
Precision |
.NET Framework type |
---|---|---|---|

double |
±5.0 × 10−324 to ±1.7 × 10308 |
15-16 digits |

## Literals

By default, a real numeric literal on the right side of the assignment operator is treated as double. However, if you want an integer number to be treated as double, use the suffix d or D, for example:

```
double x = 3D;
```

## Conversions

You can mix numeric 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 bool in relational or Boolean expressions.

If there is no double type in the expression, it evaluates to float, or bool in relational or Boolean expressions.

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 Web site.

## Example

In the following example, an int, a short, a float, and a double are added together giving a double result.

```
// Mixing types in expressions
class MixedTypes
{
static void Main()
{
int x = 3;
float y = 4.5f;
short z = 5;
double w = 1.7E+3;
// Result of the 2nd argument is a double:
Console.WriteLine("The sum is {0}", x + y + z + w);
}
}
// Output: The sum is 1712.5
```

## C# Language Specification

For more information, see the following sections in the C# Language Specification:

1.3 Types and Variables

4.1.5 Integral Types

## See Also

#### Concepts

#### Reference

Built-In Types Table (C# Reference)

Implicit Numeric Conversions Table (C# Reference)

Explicit Numeric Conversions Table (C# Reference)