Export (0) Print
Expand All

Double.Parse Method (String)

Converts the string representation of a number to its double-precision floating-point number equivalent.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static double Parse(
	string s
)

Parameters

s
Type: System.String

A string that contains a number to convert.

Return Value

Type: System.Double
A double-precision floating-point number that is equivalent to the numeric value or symbol specified in s.

ExceptionCondition
ArgumentNullException

s is null.

FormatException

s does not represent a number in a valid format.

OverflowException

s represents a number that is less than MinValue or greater than MaxValue.

The s parameter can contain the current culture's NumberFormatInfo.PositiveInfinitySymbol, NumberFormatInfo.NegativeInfinitySymbol, NumberFormatInfo.NaNSymbol, or a string of the form:

[ws][sign][integral-digits[,]]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]

Elements in square brackets ([ and ]) are optional. The following table describes each element.

Element

Description

ws

A series of white-space characters.

sign

A negative sign symbol (-) or a positive sign symbol (+). Only a leading sign can be used.

integral-digits

A series of digits ranging from 0 to 9 that specify the integral part of the number. Runs of integral-digits can be partitioned by a group-separator symbol. For example, in some cultures a comma (,) separates groups of thousands. The integral-digits element can be absent if the string contains the fractional-digits element.

,

A culture-specific thousands separator symbol.

.

A culture-specific decimal point symbol.

fractional-digits

A series of digits ranging from 0 to 9 that specify the fractional part of the number.

E

The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation.

exponential-digits

A series of digits ranging from 0 to 9 that specify an exponent.

The s parameter is interpreted using a combination of the NumberStyles.Float and NumberStyles.AllowThousands flags. This means that white space and thousands separators are allowed, for example, while currency symbols are not. For finer control over which style elements are permitted in s for the parse operation to succeed, call the Double.Parse(String, NumberStyles) or the Double.Parse(String, NumberStyles, IFormatProvider) method.

The s parameter is interpreted using the formatting information in a NumberFormatInfo object that is initialized for the current thread culture. For more information, see CurrentInfo. To parse a string using the formatting information of some other culture, call the Double.Parse(String, IFormatProvider) or Double.Parse(String, NumberStyles, IFormatProvider) method.

Ordinarily, if you pass the Double.Parse method a string that is created by calling the Double.ToString method, the original Double value is returned. However, because of a loss of precision, the values may not be equal. In addition, attempting to parse the string representation of either MinValue or MaxValue throws an OverflowException, as the following example illustrates.

   string value;

   value = Double.MinValue.ToString();
   try {
      Console.WriteLine(Double.Parse(value));
   }   
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Double type.",
                        value);
   }

   value = Double.MaxValue.ToString();
   try {
      Console.WriteLine(Double.Parse(value));
   }
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Double type.",
                        value);
   }
// The example displays the following output: 
//    -1.79769313486232E+308 is outside the range of the Double type. 
//    1.79769313486232E+308 is outside the range of the Double type.

If a separator is encountered in the s parameter during a parse operation, and the applicable currency or number decimal and group separators are the same, the parse operation assumes that the separator is a decimal separator rather than a group separator. For more information about separators, see CurrencyDecimalSeparator, NumberDecimalSeparator, CurrencyGroupSeparator, and NumberGroupSeparator.

The following example illustrates the use of the Parse(String) method.

	public class Temperature {
		// Parses the temperature from a string in form 
		// [ws][sign]digits['F|'C][ws] 
		public static Temperature Parse(string s) {
			Temperature temp = new Temperature();

			if( s.TrimEnd(null).EndsWith("'F") ) {
				temp.Value = Double.Parse( s.Remove(s.LastIndexOf('\''), 2) );
			}
			else if( s.TrimEnd(null).EndsWith("'C") ) {
				temp.Celsius = Double.Parse( s.Remove(s.LastIndexOf('\''), 2) );
			}
			else {
				temp.Value = Double.Parse(s);
			}

			return temp;
		}

		// The value holder 
		protected double m_value;

		public double Value {
			get {
				return m_value;
			}
			set {
				m_value = value;
			}
		}

		public double Celsius {
			get {
				return (m_value-32.0)/1.8;
			}
			set {
				m_value = 1.8*value+32.0;
			}
		}
	}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Show:
© 2014 Microsoft