Converts the string representation of a number in a specified style and culture-specific format to its double-precision floating-point number equivalent.
public:
static double Parse(System::String ^ s, System::Globalization::NumberStyles style, IFormatProvider ^ provider);
public:
static double Parse(System::String ^ s, System::Globalization::NumberStyles style, IFormatProvider ^ provider) = System::Numerics::INumberBase<double>::Parse;
public static double Parse(string s, System.Globalization.NumberStyles style, IFormatProvider provider);
public static double Parse(string s, System.Globalization.NumberStyles style, IFormatProvider? provider);
static member Parse : string * System.Globalization.NumberStyles * IFormatProvider -> double
Public Shared Function Parse (s As String, style As NumberStyles, provider As IFormatProvider) As Double
Parameters
A string that contains a number to convert.
A bitwise combination of enumeration values that indicate the style elements that can be present in s
. A typical value to specify is Float combined with AllowThousands.
An object that supplies culture-specific formatting information about s
.
A double-precision floating-point number that is equivalent to the numeric value or symbol specified in s
.
s
does not represent a numeric value.
The following example illustrates the use of the Parse(String, NumberStyles, IFormatProvider) method to assign several string representations of temperature values to a Temperature
object.
using System;
using System.Globalization;
public class Temperature
{
// Parses the temperature from a string. Temperature scale is
// indicated by 'F (for Fahrenheit) or 'C (for Celsius) at the end
// of the string.
public static Temperature Parse(string s, NumberStyles styles,
IFormatProvider provider)
{
Temperature temp = new Temperature();
if (s.TrimEnd(null).EndsWith("'F"))
{
temp.Value = Double.Parse(s.Remove(s.LastIndexOf((char)39), 2),
styles, provider);
}
else
{
if (s.TrimEnd(null).EndsWith("'C"))
temp.Celsius = Double.Parse(s.Remove(s.LastIndexOf((char)39), 2),
styles, provider);
else
temp.Value = Double.Parse(s, styles, provider);
}
return temp;
}
// Declare private constructor so Temperature so only Parse method can
// create a new instance
private Temperature() {}
protected double m_value;
public double Value
{
get { return m_value; }
private set { m_value = value; }
}
public double Celsius
{
get { return (m_value - 32) / 1.8; }
private set { m_value = value * 1.8 + 32; }
}
public double Fahrenheit
{
get {return m_value; }
}
}
public class TestTemperature
{
public static void Main()
{
string value;
NumberStyles styles;
IFormatProvider provider;
Temperature temp;
value = "25,3'C";
styles = NumberStyles.Float;
provider = CultureInfo.CreateSpecificCulture("fr-FR");
temp = Temperature.Parse(value, styles, provider);
Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.",
temp.Fahrenheit, temp.Celsius);
value = " (40) 'C";
styles = NumberStyles.AllowLeadingWhite | NumberStyles.AllowTrailingWhite
| NumberStyles.AllowParentheses;
provider = NumberFormatInfo.InvariantInfo;
temp = Temperature.Parse(value, styles, provider);
Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.",
temp.Fahrenheit, temp.Celsius);
value = "5,778E03'C"; // Approximate surface temperature of the Sun
styles = NumberStyles.AllowDecimalPoint | NumberStyles.AllowThousands |
NumberStyles.AllowExponent;
provider = CultureInfo.CreateSpecificCulture("en-GB");
temp = Temperature.Parse(value, styles, provider);
Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.",
temp.Fahrenheit.ToString("N"), temp.Celsius.ToString("N"));
}
}
open System
open System.Globalization
// Declare private constructor so Temperature so only Parse method can create a new instance
type Temperature private () =
let mutable m_value = 0.
member _.Value
with get () = m_value
and private set (value) = m_value <- value
member _.Celsius
with get() = (m_value - 32.) / 1.8
and private set (value) = m_value <- value * 1.8 + 32.
member _.Fahrenheit =
m_value
// Parses the temperature from a string. Temperature scale is
// indicated by 'F (for Fahrenheit) or 'C (for Celsius) at the end
// of the string.
static member Parse(s: string, styles: NumberStyles, provider: IFormatProvider) =
let temp = new Temperature()
if s.TrimEnd(null).EndsWith "'F" then
temp.Value <- Double.Parse(s.Remove(s.LastIndexOf(char 39), 2), styles, provider)
else
if s.TrimEnd(null).EndsWith "'C" then
temp.Celsius <- Double.Parse(s.Remove(s.LastIndexOf(char 39), 2), styles, provider)
else
temp.Value <- Double.Parse(s, styles, provider)
temp
[<EntryPoint>]
let main _ =
let value = "25,3'C"
let styles = NumberStyles.Float
let provider = CultureInfo.CreateSpecificCulture "fr-FR"
let temp = Temperature.Parse(value, styles, provider)
printfn $"{temp.Fahrenheit} degrees Fahrenheit equals {temp.Celsius} degrees Celsius."
let value = " (40) 'C"
let styles = NumberStyles.AllowLeadingWhite ||| NumberStyles.AllowTrailingWhite ||| NumberStyles.AllowParentheses
let provider = NumberFormatInfo.InvariantInfo
let temp = Temperature.Parse(value, styles, provider)
printfn $"{temp.Fahrenheit} degrees Fahrenheit equals {temp.Celsius} degrees Celsius."
let value = "5,778E03'C" // Approximate surface temperature of the Sun
let styles = NumberStyles.AllowDecimalPoint ||| NumberStyles.AllowThousands ||| NumberStyles.AllowExponent
let provider = CultureInfo.CreateSpecificCulture "en-GB"
let temp = Temperature.Parse(value, styles, provider)
printfn $"{temp.Fahrenheit:N} degrees Fahrenheit equals {temp.Celsius:N} degrees Celsius."
0
Imports System.Globalization
Public Class Temperature
' Parses the temperature from a string. Temperature scale is
' indicated by 'F (for Fahrenheit) or 'C (for Celsius) at the end
' of the string.
Public Shared Function Parse(s As String, styles As NumberStyles, _
provider As IFormatProvider) As Temperature
Dim temp As New Temperature()
If s.TrimEnd(Nothing).EndsWith("'F") Then
temp.Value = Double.Parse(s.Remove(s.LastIndexOf("'"c), 2), _
styles, provider)
Else
If s.TrimEnd(Nothing).EndsWith("'C") Then
temp.Celsius = Double.Parse(s.Remove(s.LastIndexOf("'"c), 2), _
styles, provider)
Else
temp.Value = Double.Parse(s, styles, provider)
End If
End If
Return temp
End Function
' Declare private constructor so Temperature so only Parse method can
' create a new instance
Private Sub New
End Sub
Protected m_value As Double
Public Property Value() As Double
Get
Return m_value
End Get
Private Set
m_value = Value
End Set
End Property
Public Property Celsius() As Double
Get
Return (m_value - 32) / 1.8
End Get
Private Set
m_value = Value * 1.8 + 32
End Set
End Property
Public ReadOnly Property Fahrenheit() As Double
Get
Return m_Value
End Get
End Property
End Class
Public Module TestTemperature
Public Sub Main
Dim value As String
Dim styles As NumberStyles
Dim provider As IFormatProvider
Dim temp As Temperature
value = "25,3'C"
styles = NumberStyles.Float
provider = CultureInfo.CreateSpecificCulture("fr-FR")
temp = Temperature.Parse(value, styles, provider)
Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.", _
temp.Fahrenheit, temp.Celsius)
value = " (40) 'C"
styles = NumberStyles.AllowLeadingWhite Or NumberStyles.AllowTrailingWhite _
Or NumberStyles.AllowParentheses
provider = NumberFormatInfo.InvariantInfo
temp = Temperature.Parse(value, styles, provider)
Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.", _
temp.Fahrenheit, temp.Celsius)
value = "5,778E03'C" ' Approximate surface temperature of the Sun
styles = NumberStyles.AllowDecimalPoint Or NumberStyles.AllowThousands Or _
NumberStyles.AllowExponent
provider = CultureInfo.CreateSpecificCulture("en-GB")
temp = Temperature.Parse(value, styles, provider)
Console.WriteLine("{0} degrees Fahrenheit equals {1} degrees Celsius.", _
temp.Fahrenheit.ToString("N"), temp.Celsius.ToString("N"))
End Sub
End Module
Remarks
In .NET Core 3.0 and later, values that are too large to represent are rounded to PositiveInfinity or NegativeInfinity as required by the IEEE 754 specification. In prior versions, including .NET Framework, parsing a value that was too large to represent resulted in failure.
The style
parameter defines the style elements (such as white space, thousands separators, and currency symbols) that are allowed in the s
parameter for the parse operation to succeed. It must be a combination of bit flags from the NumberStyles enumeration. The following NumberStyles members are not supported:
The s
parameter can contain NumberFormatInfo.PositiveInfinitySymbol, NumberFormatInfo.NegativeInfinitySymbol, or NumberFormatInfo.NaNSymbol for the culture specified by provider
. Depending on the value of style
, it can also take the form:
[ws] [$] [sign][integral-digits,]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]
Elements framed in square brackets ([ and ]) are optional. The following table describes each element.
Element Description ws A series of white-space characters. White space can appear at the beginning ofs
if style
includes the NumberStyles.AllowLeadingWhite flag, and it can appear at the end of s
if style
includes the NumberStyles.AllowTrailingWhite flag. $ A culture-specific currency symbol. Its position in the string is defined by the NumberFormatInfo.CurrencyNegativePattern and NumberFormatInfo.CurrencyPositivePattern properties of the current culture. The current culture's currency symbol can appear in s
if style
includes the NumberStyles.AllowCurrencySymbol flag. sign A negative sign symbol (-) or a positive sign symbol (+). The sign can appear at the beginning of s
if style
includes the NumberStyles.AllowLeadingSign flag, and it can appear at the end of s
if style
includes the NumberStyles.AllowTrailingSign flag. Parentheses can be used in s
to indicate a negative value if style
includes the NumberStyles.AllowParentheses flag. integral-digits A series of digits ranging from 0 to 9 that specify the integral part of the number. The integral-digits element can be absent if the string contains the fractional-digits element. , A culture-specific group separator. The current culture's group separator symbol can appear in s
if style
includes the NumberStyles.AllowThousands flag . A culture-specific decimal point symbol. The current culture's decimal point symbol can appear in s
if style
includes the NumberStyles.AllowDecimalPoint flag. fractional-digits A series of digits ranging from 0 to 9 that specify the fractional part of the number. Fractional digits can appear in s
if style
includes the NumberStyles.AllowDecimalPoint flag. E The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation. The s
parameter can represent a number in exponential notation if style
includes the NumberStyles.AllowExponent flag. exponential-digits A series of digits ranging from 0 to 9 that specify an exponent.
Note
Any terminating NUL (U+0000) characters in s
are ignored by the parsing operation, regardless of the value of the style
argument.
A string with digits only (which corresponds to the NumberStyles.None style) always parses successfully if it is in the range of the Double type. The remaining System.Globalization.NumberStyles members control elements that may be present, but are not required to be present, in the input string. The following table indicates how individual NumberStyles flags affect the elements that may be present in s
.
s
in addition to digits None The integral-digits element only. AllowDecimalPoint The decimal point (.) and fractional-digits elements. AllowExponent The "e" or "E" character, which indicates exponential notation. This flag by itself supports values in the form digitsEdigits; additional flags are needed to successfully parse strings with such elements as positive or negative signs and decimal point symbols. AllowLeadingWhite The ws element at the beginning of s
. AllowTrailingWhite The ws element at the end of s
. AllowLeadingSign The sign element at the beginning of s
. AllowTrailingSign The sign element at the end of s
. AllowParentheses The sign element in the form of parentheses enclosing the numeric value. AllowThousands The thousands separator (,) element. AllowCurrencySymbol The currency ($) element. Currency All elements. However, s
cannot represent a hexadecimal number or a number in exponential notation. Float The ws element at the beginning or end of s
, sign at the beginning of s
, and the decimal point (.) symbol. The s
parameter can also use exponential notation. Number The ws
, sign
, thousands separator (,) and decimal point (.) elements. Any All elements. However, s
cannot represent a hexadecimal number.
The provider
parameter is an IFormatProvider implementation whose GetFormat method returns a NumberFormatInfo object that supplies culture-specific information used in interpreting the format of s
. Typically, it is a NumberFormatInfo or CultureInfo object. If provider
is null
or a NumberFormatInfo cannot be obtained, the formatting information for the current system culture is used.
Ordinarily, if you pass the Double.Parse method a string that is created by calling the Double.ToString method, the original Double value is returned. However, because of a loss of precision, the values may not be equal. In addition, attempting to parse the string representation of either MinValue or Double.MaxValue fails to round-trip. On .NET Framework and .NET Core 2.2 and previous versions, it throws an OverflowException. On .NET Core 3.0 and later versions, it returns Double.NegativeInfinity if you attempt to parse MinValue or Double.PositiveInfinity if you attempt to parse MaxValue. The following example provides an illustration.
string value;
value = Double.MinValue.ToString();
try {
Console.WriteLine(Double.Parse(value));
}
catch (OverflowException) {
Console.WriteLine($"{value} is outside the range of the Double type.");
}
value = Double.MaxValue.ToString();
try {
Console.WriteLine(Double.Parse(value));
}
catch (OverflowException) {
Console.WriteLine($"{value} is outside the range of the Double type.");
}
// Format without the default precision.
value = Double.MinValue.ToString("G17");
try
{
Console.WriteLine(Double.Parse(value));
}
catch (OverflowException)
{
Console.WriteLine($"{value} is outside the range of the Double type.");
}
// 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.
// -1.79769313486232E+308
open System
[<EntryPoint>]
let main _ =
let value = string Double.MinValue
try
printfn $"{Double.Parse value}"
with :? OverflowException ->
printfn $"{value} is outside the range of the Double type."
let value = string Double.MaxValue
try
printfn $"{Double.Parse value}"
with :? OverflowException ->
printfn $"{value} is outside the range of the Double type."
// Format without the default precision.
let value = Double.MinValue.ToString "G17"
try
printfn $"{Double.Parse value}"
with :? OverflowException ->
printfn $"{value} is outside the range of the Double type."
0
// The example displays the following output:
// -1.79769313486232E+308 is outside the range of the Double type.
// 1.79769313486232E+308 is outside the range of the Double type.
// -1.79769313486232E+308
Dim value As String
value = Double.MinValue.ToString()
Try
Console.WriteLine(Double.Parse(value))
Catch e As OverflowException
Console.WriteLine($"{value} is outside the range of the Double type.")
End Try
value = Double.MaxValue.ToString()
Try
Console.WriteLine(Double.Parse(value))
Catch e As OverflowException
Console.WriteLine($"{value} is outside the range of the Double type.")
End Try
' Format without the default precision.
value = Double.MinValue.ToString("G17")
Try
Console.WriteLine(Double.Parse(value))
Catch e As OverflowException
Console.WriteLine($"{value} is outside the range of the Double type.")
End Try
' 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.
' -1.79769313486232E+308
On .NET Framework and .NET Core 2.2 and earlier versions, if s
is out of range of the Double data type, the Parse(String, NumberStyles, IFormatProvider) method throws an OverflowException.
On .NET Core 3.0 and later versions, no exception is thrown when s
is out of range of the Double data type. In most cases, the Parse(String, NumberStyles, IFormatProvider) method will return Double.PositiveInfinity or Double.NegativeInfinity. However, there is a small set of values that are considered to be closer to the maximum or minimum values of Double than to positive or negative infinity. In those cases, the method returns Double.MaxValue or Double.MinValue.
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.
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