Convert.ToDouble Method (String)
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Converts the specified String representation of a number to an equivalent double-precision floating point number.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
- Type: System.String
A String containing a number to convert.
Return Value
Type: System.DoubleA double-precision floating point number equivalent to the value of value.
-or-
Zero if value is Nothing.
| Exception | Condition |
|---|---|
| FormatException | value is not a number in a valid format. |
| OverflowException | value represents a number less than MinValue or greater than MaxValue. |
The return value is the result of invoking the Double.Parse method on value.
If you prefer not to handle an exception if the conversion fails, you can call the Double.TryParse method instead. It returns a Boolean value that indicates whether the conversion succeeded or failed.
The following code sample illustrates the conversion of a String value to a Double one, using ToDouble.
Public Sub CovertDoubleFloat(ByVal doubleVal As Double) Dim singleVal As Single = 0 ' Double to Single conversion cannot overflow. singleVal = System.Convert.ToSingle(doubleVal) outputBlock.Text &= String.Format("{0} as a Single is {1}", _ doubleVal, singleVal) & vbCrLf ' Conversion from Single to Double cannot overflow. doubleVal = System.Convert.ToDouble(singleVal) outputBlock.Text &= String.Format("{0} as a Double is: {1}", _ singleVal, doubleVal) & vbCrLf End Sub ... Public Sub ConvertDoubleString(ByVal doubleVal As Double) Dim stringVal As String ' A conversion from Double to String cannot overflow. stringVal = System.Convert.ToString(doubleVal) outputBlock.Text &= String.Format("{0} as a String is: {1}", _ doubleVal, stringVal) & vbCrLf Try doubleVal = System.Convert.ToDouble(stringVal) outputBlock.Text &= String.Format("{0} as a Double is: {1}", _ stringVal, doubleVal) & vbCrLf Catch exception As System.OverflowException outputBlock.Text &= String.Format( _ "Overflow in String-to-Double conversion.") & vbCrLf Catch exception As System.FormatException outputBlock.Text &= String.Format( _ "The string is not formatted as a Double.") & vbCrLf Catch exception As System.ArgumentException outputBlock.Text &= "The string is null." & vbCrLf End Try End Sub