Single::TryParse Method (String, NumberStyles, IFormatProvider, Single%)
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 value indicates whether the conversion succeeded or failed.
Assembly: mscorlib (in mscorlib.dll)
public: static bool TryParse( String^ s, NumberStyles style, IFormatProvider^ provider, [OutAttribute] float% result )
- Type: System::String
A string representing a number to convert.
- Type: System.Globalization::NumberStyles
- Type: System::IFormatProvider
An object that supplies culture-specific formatting information about s.
- 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 nullptr or String::Empty, is not in a format compliant with style, represents a number less than Single::MinValue or greater than Single::MaxValue, or if style is not a valid combination of NumberStyles enumerated constants. This parameter is passed uninitialized.
Return ValueType: System::Boolean
true if s was converted successfully; otherwise, false.
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, 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.
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.
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.
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.
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.
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.
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.
Elements permitted in s in addition to digits
The integral-digits element only.
The . and fractional-digits elements.
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.
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 , element.
The $ element.
All. The s parameter 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 . symbol. The s parameter can also use exponential notation.
The ws, sign, thousands separator (,), and decimal point (.) elements.
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 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.
If provider is nullptr, 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.
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.