Single.Parse Method (String, NumberStyles)
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Converts the string representation of a number in a specified style to its single-precision floating-point number equivalent.
Assembly: mscorlib (in mscorlib.dll)
'Declaration Public Shared Function Parse ( _ s As String, _ style As NumberStyles _ ) As Single
Parameters
- s
- Type: System.String
A string representing a number to convert.
- style
- Type: System.Globalization.NumberStyles
A bitwise combination of enumeration values that indicates the style elements that can be present in s. A typical value to specify is NumberStyles.Float combined with NumberStyles.AllowThousands.
Return Value
Type: System.SingleA single-precision floating-point number that is equivalent to the numeric value or symbol specified in s.
| Exception | Condition |
|---|---|
| ArgumentNullException | s is Nothing. |
| FormatException | s is not a number in a valid format. |
| OverflowException | s represents a number less than MinValue or greater than MaxValue. |
| ArgumentException | style is not a NumberStyles value. -or- style is the AllowHexSpecifier value. |
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 the current culture's PositiveInfinitySymbol, NegativeInfinitySymbol, NaNSymbol. Depending on the value of style, it can also take the form:
[ws][$][sign][integral-digits[,]]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]
Elements in square brackets ([ and ]) are optional. The following table describes each element.
A string with digits only (which corresponds to the NumberStyles.None style) always parses successfully. The remaining System.Globalization.NumberStyles members control elements that may be present, but are not required to be present, in the input string. The following table indicates how individual NumberStyles flags affect the elements that may be present in s.
NumberStyles value | Elements permitted in s in addition to digits |
|---|---|
The integral-digits element only. | |
The decimal point (.) and fractional-digits elements. | |
The "e" or "E" character, which indicates exponential notation. This flag by itself supports values in the form digitsEdigits; additional flags are needed to successfully parse strings with such elements as positive or negative signs and decimal point symbols. | |
The ws element at the beginning of s. | |
The ws element at the end of s. | |
The sign element at the beginning of s. | |
The sign element at the end of s. | |
The sign element in the form of parentheses enclosing the numeric value. | |
The thousands separator (,) element. | |
The currency ($) element. | |
All elements. However, s cannot represent a hexadecimal number or a number in exponential notation. | |
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. | |
The ws, sign, thousands separator (,) and decimal point (.) elements. | |
All elements. However, s cannot represent a hexadecimal number. |
Some examples of s are "100", "-123,456,789", "123.45e+6", "+500", "5e2", "3.1416", "600.", "-.123", and "-Infinity".
The s parameter is parsed using the formatting information in a NumberFormatInfo object that is initialized for the current system culture. To specify the culture whose formatting information is used for the parse operation, call the Parse(String, NumberStyles, IFormatProvider) overload.
Ordinarily, if you pass the Parse method a string that is created by calling the ToString method, the original Single value is returned. However, because of a loss of precision, the values may not be equal.
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 code example parses String representations of Single values with the Parse method, using NumberStyles values.
' Example of the Single.Parse( ) methods. Imports System.Globalization Module Example ' Get the exception type name; remove the namespace prefix. Function GetExceptionType(ByVal ex As Exception) As String Dim exceptionType As String = ex.GetType().ToString() Return exceptionType.Substring( _ exceptionType.LastIndexOf("."c) + 1) End Function Sub SingleParse(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal styles As NumberStyles, _ ByVal provider As IFormatProvider) Dim singleFormats As String() = { _ " 987.654E-2", " 987,654E-2", "(98765,43210)", _ "9,876,543.210", "9.876.543,210", "98_76_54_32,19"} ' Parse each string in the singleFormats array, using ' NumberStyles and IFormatProvider, if specified. Dim singleString As String For Each singleString In singleFormats Dim singleNumber As Single ' Display the first part of the output line. outputBlock.Text &= String.Format(" Parse of {0,-20}", _ String.Format("""{0}""", singleString)) ' Use the appropriate Single.Parse overload, based on ' the parameters that are specified. Try If provider Is Nothing Then If styles < 0 Then singleNumber = Single.Parse(singleString) Else singleNumber = _ Single.Parse(singleString, styles) End If ElseIf styles < 0 Then singleNumber = _ Single.Parse(singleString, provider) Else singleNumber = Single.Parse( _ singleString, styles, provider) End If ' Display the resulting value if Parse succeeded. outputBlock.Text &= String.Format("success: {0}", singleNumber) & vbCrLf ' Display the exception type if Parse failed. Catch ex As Exception outputBlock.Text &= String.Format("failed: {0}", _ GetExceptionType(ex)) & vbCrLf End Try Next singleString End Sub Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) outputBlock.Text &= String.Format("This example of" & vbCrLf & _ " Single.Parse( String )," & vbCrLf & _ " Single.Parse( String, NumberStyles )," & vbCrLf & _ " Single.Parse( String, IFormatProvider ), and" & _ vbCrLf & " Single.Parse( String, NumberStyles, " & _ "IFormatProvider )" & vbCrLf & "generates the " & _ "following output when run in the [{0}] culture.", _ CultureInfo.CurrentCulture.Name) & vbCrLf outputBlock.Text &= String.Format("Several string representations " & _ "of Single values are parsed.") & vbCrLf ' Do not use IFormatProvider or NumberStyles. outputBlock.Text &= String.Format(vbCrLf & _ "NumberStyles and IFormatProvider are not " & _ "used; current culture is [{0}]:", _ CultureInfo.CurrentCulture.Name) & vbCrLf SingleParse(outputBlock, CType(-1, NumberStyles), Nothing) ' Use the NumberStyle for Currency. outputBlock.Text &= String.Format(vbCrLf & "NumberStyles.Currency " & _ "is used; IFormatProvider is not used:") & vbCrLf SingleParse(outputBlock, NumberStyles.Currency, Nothing) ' Create a CultureInfo object for another culture. Use ' [Dutch - The Netherlands] unless the current culture ' is Dutch language. In that case use [English - U.S.]. Dim cultureName As String = IIf( _ CultureInfo.CurrentCulture.Name.Substring(0, 2) = _ "nl", "en-US", "nl-NL") Dim culture As New CultureInfo(cultureName) outputBlock.Text &= String.Format(vbCrLf & _ "NumberStyles is not used; [{0}] culture " & _ "IFormatProvider is used:", culture.Name) & vbCrLf SingleParse(outputBlock, CType(-1, NumberStyles), culture) ' Get the NumberFormatInfo object from CultureInfo, and ' then change the digit group size to 2 and the digit ' separator to '_'. Dim numInfo As NumberFormatInfo = culture.NumberFormat numInfo.NumberGroupSizes = New Integer() {2} numInfo.NumberGroupSeparator = "_" ' Use the NumberFormatInfo object as the IFormatProvider. outputBlock.Text &= String.Format(vbCrLf & _ "NumberStyles.Currency is used, group size = 2, " & _ "separator = ""_"":") & vbCrLf SingleParse(outputBlock, NumberStyles.Currency, numInfo) End Sub End Module ' This example of ' Single.Parse( String ), ' Single.Parse( String, NumberStyles ), ' Single.Parse( String, IFormatProvider ), and ' Single.Parse( String, NumberStyles, IFormatProvider ) ' generates the following output when run in the [en-US] culture. ' Several string representations of Single values are parsed. ' ' NumberStyles and IFormatProvider are not used; current culture is [en-US]: ' Parse of " 987.654E-2" success: 9.87654 ' Parse of " 987,654E-2" success: 9876.54 ' Parse of "(98765,43210)" failed: FormatException ' Parse of "9,876,543.210" success: 9876543 ' Parse of "9.876.543,210" failed: FormatException ' Parse of "98_76_54_32,19" failed: FormatException ' ' NumberStyles.Currency is used; IFormatProvider is not used: ' Parse of " 987.654E-2" failed: FormatException ' Parse of " 987,654E-2" failed: FormatException ' Parse of "(98765,43210)" success: -9.876543E+09 ' Parse of "9,876,543.210" success: 9876543 ' Parse of "9.876.543,210" failed: FormatException ' Parse of "98_76_54_32,19" failed: FormatException ' ' NumberStyles is not used; [nl-NL] culture IFormatProvider is used: ' Parse of " 987.654E-2" success: 9876.54 ' Parse of " 987,654E-2" success: 9.87654 ' Parse of "(98765,43210)" failed: FormatException ' Parse of "9,876,543.210" failed: FormatException ' Parse of "9.876.543,210" success: 9876543 ' Parse of "98_76_54_32,19" failed: FormatException ' ' NumberStyles.Currency is used, group size = 2, separator = "_": ' Parse of " 987.654E-2" failed: FormatException ' Parse of " 987,654E-2" failed: FormatException ' Parse of "(98765,43210)" success: -98765.43 ' Parse of "9,876,543.210" failed: FormatException ' Parse of "9.876.543,210" success: 9876543 ' Parse of "98_76_54_32,19" success: 9.876543E+07