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.NET Development
.NET Framework 3.5
System Namespace
Convert Class
Convert Methods
ToDouble Method
 ToDouble Method (Single)

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This page is specific to
Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:
.NET Framework Class Library
Convert..::.ToDouble Method (Single)

Converts the value of the specified single-precision floating-point number to an equivalent double-precision floating-point number.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
Visual Basic (Declaration)
Public Shared Function ToDouble ( _
    value As Single _
) As Double
Visual Basic (Usage)
Dim value As Single
Dim returnValue As Double

returnValue = Convert.ToDouble(value)
C#
public static double ToDouble(
    float value
)
Visual C++
public:
static double ToDouble(
    float value
)
JScript
public static function ToDouble(
    value : float
) : double

Parameters

value
Type: System..::.Single
The single-precision floating-point number.

Return Value

Type: System..::.Double
A double-precision floating-point number that is equivalent to value.

The following example converts a Single value to a Double value.

Visual Basic
Public Sub CovertDoubleFloat(ByVal doubleVal As Double)
    Dim singleVal As Single = 0

    ' Double to Single conversion cannot overflow.
        singleVal = System.Convert.ToSingle(doubleVal)
        System.Console.WriteLine("{0} as a Single is {1}", _
                                  doubleVal, singleVal)

    ' Conversion from Single to Double cannot overflow.
    doubleVal = System.Convert.ToDouble(singleVal)
    System.Console.WriteLine("{0} as a Double is: {1}", _
                              singleVal, doubleVal)
End Sub

C#
        public void CovertDoubleFloat(double doubleVal) {    
            float floatVal = 0;

            // Double to float conversion cannot overflow.
                floatVal = System.Convert.ToSingle(doubleVal);
                System.Console.WriteLine("{0} as a float is {1}",
                    doubleVal, floatVal);

            // Conversion from float to double cannot overflow.
            doubleVal = System.Convert.ToDouble(floatVal);
            System.Console.WriteLine("{0} as a double is: {1}",
                floatVal, doubleVal);
        }

Visual C++
public:
   void CovertDoubleFloat( double doubleVal )
   {
      float floatVal = 0;

      // A conversion from Double to Single cannot overflow.
      floatVal = System::Convert::ToSingle( doubleVal );
      System::Console::WriteLine( " {0} as a float is {1}",
                                  doubleVal, floatVal );

      // A conversion from Single to Double cannot overflow.
      doubleVal = System::Convert::ToDouble( floatVal );
      System::Console::WriteLine( " {0} as a double is: {1}",
                                  floatVal, doubleVal );
   }

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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Be aware of the precision loss issue      Darkthread ... CatZimmermann   |   Edit   |   Show History
9.3F cannot be represented exactly in either single or double precision.

Although double has "DOUBLE" precision than single, you may lose some precision as converting single to double. For example, Convert.ToDouble(9.3F) will return 9.30000019073486, but not 9.3. Maybe it's by design, you should be aware of it.
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