• Article

Single.TryParse Method (String, NumberStyles, IFormatProvider, Single%)

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Converts the string representation of a number in a specified style and culture-specific format to its single-precision floating-point number equivalent. A return code indicates whether the conversion succeeded or failed.

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

Syntax

'Declaration
Public Shared Function TryParse ( _
    s As String, _
    style As NumberStyles, _
    provider As IFormatProvider, _
    <OutAttribute> ByRef result As Single _
) As Boolean

public static bool TryParse(
    string s,
    NumberStyles style,
    IFormatProvider provider,
    out float result
)

Parameters

  • s
    Type: System.String
    A string representing a number to convert.
  • provider
    Type: System.IFormatProvider
    An object that supplies culture-specific formatting information about s.
  • result
    Type: System.Single%
    When this method returns, contains the single-precision floating-point number equivalent to the numeric value or symbol contained in s, if the conversion succeeded, or zero if the conversion failed. The conversion fails if the s parameter is nulla null reference (Nothing in Visual Basic), is not in a format compliant with style, represents a number less than MinValue or greater than MaxValue, or if style is not a valid combination of NumberStyles enumerated constants. This parameter is passed uninitialized.

Return Value

Type: System.Boolean
true if s was converted successfully; otherwise, false.

Exceptions

Exception Condition
ArgumentException

style is not a NumberStyles value.

-or-

style is the AllowHexSpecifier value.

Remarks

This overload differs from the Parse(String, NumberStyles, IFormatProvider) method by returning a Boolean value that indicates whether the parse operation succeeded instead of returning the parsed numeric value. It eliminates the need to use exception handling to test for a FormatException in the event that s is invalid and cannot be successfully parsed.

The style parameter defines the allowable format of 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 PositiveInfinitySymbol, NegativeInfinitySymbol, or NaNSymbol for the culture indicated by provider. In addition, depending on the value of style, the s parameter may include the following elements:

[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

Optional white space. White space can appear at the beginning of s if style includes the NumberStyles.AllowLeadingWhite flag. 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 or NumberFormatInfo.CurrencyPositivePattern properties of the NumberFormatInfo object returned by the IFormatProvider.GetFormat method of the provider parameter. The currency symbol can appear in s if style includes the NumberStyles.AllowCurrencySymbol flag.

sign

An optional sign. 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. Integral-digits can be absent if there are fractional-digits.

,

A culture-specific thousands separator symbol. The current culture's thousands 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 s can represent a number using exponential 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.

A string with digits only (which corresponds to the NumberStyles.None style) always parses successfully. The remaining System.Globalization.NumberStyles members control elements that may be 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.

NumberStyles value

Elements permitted in s in addition to digits

None

The integral-digits element only.

AllowDecimalPoint

The . and fractional-digits elements.

AllowExponent

The s parameter can also use exponential notation. This flag by itself supports values in the form integral-digitsEexponential-digits; additional flags are needed to successfully parse strings in exponential notation 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 , element.

AllowCurrencySymbol

The $ element.

Currency

All. The s parameter 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 . symbol. The s parameter can also use exponential notation.

Number

The ws, sign, thousands separator (,), and decimal point (.) elements.

Any

All styles, except s cannot represent a hexadecimal number.

The provider parameter is an IFormatProvider implementation whose GetFormat method returns a NumberFormatInfo object that provides culture-specific formatting information. When the TryParse(String, NumberStyles, IFormatProvider, Single%) method is invoked, it calls the provider parameter's GetFormat method and passes it a Type object that represents the NumberFormatInfo type. The GetFormat method then returns the NumberFormatInfo object that provides information about the format of the s parameter. There are three ways to use the provider parameter to supply custom formatting information to the parse operation:

  • You can pass a CultureInfo object that represents the culture that supplies formatting information. Its GetFormat method returns the NumberFormatInfo object that provides numeric formatting information for that culture.

  • You can pass the actual NumberFormatInfo object that provides numeric formatting information. (Its implementation of GetFormat just returns itself.)

  • You can pass a custom object that implements IFormatProvider. Its GetFormat method instantiates and returns the NumberFormatInfo object that provides formatting information.

If provider is nulla null reference (Nothing in Visual Basic), the formatting of s is interpreted based on the NumberFormatInfo object of the current culture.

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.

Examples

The following example demonstrates the use of the Single.TryParse(String, NumberStyles, IFormatProvider, Single%) method to parse the string representation of numbers that have a particular style and are formatted using the conventions of a particular culture.

Dim value As String
Dim style As System.Globalization.NumberStyles
Dim culture As System.Globalization.CultureInfo
Dim number As Single

' Parse currency value using en-GB culture.
value = "£1,097.63"
style = System.Globalization.NumberStyles.Number Or _
        System.Globalization.NumberStyles.AllowCurrencySymbol
culture = New System.Globalization.CultureInfo("en-GB")
If Single.TryParse(value, style, culture, number) Then
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf
Else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) & vbCrLf
End If

value = "1345,978"
style = System.Globalization.NumberStyles.AllowDecimalPoint
culture = New System.Globalization.CultureInfo("fr-FR")
If Single.TryParse(value, style, culture, number) Then
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf
Else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) & vbCrLf
End If

value = "1.345,978"
style = System.Globalization.NumberStyles.AllowDecimalPoint Or _
        System.Globalization.NumberStyles.AllowThousands
culture = New System.Globalization.CultureInfo("es-ES")
If Single.TryParse(value, style, culture, number) Then
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf
Else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) & vbCrLf
End If

value = "1 345,978"
If Single.TryParse(value, style, culture, number) Then
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf
Else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) & vbCrLf
End If
' The example displays the following output:
'       Converted '?1,097.63' to 1097.63.
'       Converted '1345,978' to 1345.978.
'       Converted '1.345,978' to 1345.978.
'       Unable to convert '1 345,978'.

string value;
System.Globalization.NumberStyles style;
System.Globalization.CultureInfo culture;
float number;

// Parse currency value using en-GB culture.
value = "�1,097.63";
style = System.Globalization.NumberStyles.Number |
        System.Globalization.NumberStyles.AllowCurrencySymbol;
culture = new System.Globalization.CultureInfo("en-GB");
if (Single.TryParse(value, style, culture, out number))
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";
else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) + "\n";

value = "1345,978";
style = System.Globalization.NumberStyles.AllowDecimalPoint;
culture = new System.Globalization.CultureInfo("fr-FR");
if (Single.TryParse(value, style, culture, out number))
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";
else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) + "\n";

value = "1.345,978";
style = System.Globalization.NumberStyles.AllowDecimalPoint |
        System.Globalization.NumberStyles.AllowThousands;
culture = new System.Globalization.CultureInfo("es-ES");
if (Single.TryParse(value, style, culture, out number))
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";
else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) + "\n";

value = "1 345,978";
if (Single.TryParse(value, style, culture, out number))
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";
else
   outputBlock.Text += String.Format("Unable to convert '{0}'.", value) + "\n";
// The example displays the following output:
//       Converted '�1,097.63' to 1097.63.
//       Converted '1345,978' to 1345.978.
//       Converted '1.345,978' to 1345.978.
//       Unable to convert '1 345,978'.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.