# double (C# Reference)

Visual Studio 2005

The double keyword denotes 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-hand 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 the case of relational or Boolean expressions.

• If there is no double type in the expression, it evaluates to float, or bool in the case of 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 on these values, refer to IEEE Standard for Binary Floating-Point Arithmetic, available on the Web site http://www.ieee.org/portal/index.jsp.

## Example

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

```// keyword_double.cs
// Mixing types in expressions
using System;
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