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# Convert.ToDouble Method (String)

.NET Framework 1.1

Converts the specified String representation of a number to an equivalent double-precision floating point number.

```[Visual Basic]
Overloads Public Shared Function ToDouble( _
ByVal value As String _
) As Double
[C#]
public static double ToDouble(
string value
);
[C++]
public: static double ToDouble(
String* value
);
[JScript]
public static function ToDouble(
value : String
) : double;```

#### Parameters

value
A String containing a number to convert.

#### Return Value

A double-precision floating point number equivalent to the value of value.

-or-

Zero if value is a null reference (Nothing in Visual Basic).

#### Exceptions

Exception Type Condition
FormatException value does not consist of an optional sign followed by a sequence of digits (zero through nine).
OverflowException value represents a number less than MinValue or greater than MaxValue.

#### Remarks

The return value is the result of invoking the Double.Parse method on value.

#### Example

[Visual Basic, C#, C++] The following code sample illustrates the conversion of a String value to a Double one, using ToDouble.

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

' Double to Single conversion can overflow.
Try
singleVal = System.Convert.ToSingle(doubleVal)
System.Console.WriteLine("{0} as a Single is {1}", _
doubleVal, singleVal)
Catch exception As System.OverflowException
System.Console.WriteLine( _
"Overflow in Double-to-Float conversion.")
End Try

' 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
. . .
Public Sub ConvertDoubleString(ByVal doubleVal As Double)

Dim stringVal As String

' A conversion from Double to String cannot overflow.
stringVal = System.Convert.ToString(doubleVal)
System.Console.WriteLine("{0} as a String is: {1}", _
doubleVal, stringVal)

Try
doubleVal = System.Convert.ToDouble(stringVal)
System.Console.WriteLine("{0} as a Double is: {1}", _
stringVal, doubleVal)
Catch exception As System.OverflowException
System.Console.WriteLine( _
"Overflow in String-to-Double conversion.")
Catch exception As System.FormatException
System.Console.WriteLine( _
"The string is not formatted as a Double.")
Catch exception As System.ArgumentException
System.Console.WriteLine("The string is null.")
End Try

End Sub

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

// Double to float conversion can overflow.
try {
floatVal = System.Convert.ToSingle(doubleVal);
System.Console.WriteLine("{0} as a float is {1}",
doubleVal, floatVal);
}
catch (System.OverflowException) {
System.Console.WriteLine(
"Overflow in double-to-float conversion.");
}

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

string    stringVal;

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

try {
doubleVal = System.Convert.ToDouble(stringVal);
System.Console.WriteLine("{0} as a double is: {1}",
stringVal, doubleVal);
}
catch (System.OverflowException) {
System.Console.WriteLine(
"Conversion from string-to-double overflowed.");
}
catch (System.FormatException) {
System.Console.WriteLine(
"The string was not formatted as a double.");
}
catch (System.ArgumentException) {
System.Console.WriteLine(
"The string pointed to null.");
}
}

[C++]

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

// Double to float conversion can overflow.
try {
floatVal = System::Convert::ToSingle(doubleVal);
System::Console::WriteLine(S" {0} as a float is {1}",
__box(doubleVal), __box(floatVal));
} catch (System::OverflowException*) {
System::Console::WriteLine(S"Overflow in double-to-float conversion.");
}

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

void ConvertDoubleString(double doubleVal)
{
String*    stringVal;

// A conversion from Double to String* cannot overflow.
stringVal = System::Convert::ToString(doubleVal);
System::Console::WriteLine(S" {0} as a String* is: {1}",
__box(doubleVal), stringVal);

try {
doubleVal = System::Convert::ToDouble(stringVal);
System::Console::WriteLine(S" {0} as a double is: {1}",
stringVal, __box(doubleVal));
} catch (System::OverflowException*) {
System::Console::WriteLine(S"Conversion from String*-to-double overflowed.");
} catch (System::FormatException*) {
System::Console::WriteLine(S"The String* was not formatted as a double.");
} catch (System::ArgumentException*) {
System::Console::WriteLine(S"The String* pointed to null.");
}
}
```

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button in the upper-left corner of the page.

#### Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard