Double::TryParse Method (String^, NumberStyles, IFormatProvider^, Double%)
Converts the string representation of a number in a specified style and culture-specific format to its double-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] double% result )
A string containing a number to convert.
- Type: System.Globalization::NumberStyles
An IFormatProvider that supplies culture-specific formatting information about s.
When this method returns, contains a double-precision floating-point number equivalent of 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 null or String::Empty, 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; any value originally supplied in result will be overwritten.
Return ValueType: System::Boolean
true if s was converted successfully; otherwise, false.
The Parse(String^, NumberStyles, IFormatProvider^) method, except this method does not throw an exception if the conversion fails. If the conversion succeeds, the return value is true and the result parameter is set to the outcome of the conversion. If the conversion fails, the return value is false and the result parameter is set to zero. This eliminates the need to use exception handling to test for a FormatException in the event that s is invalid and cannot be successfully parsed.method is like the
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 NumberFormatInfo::PositiveInfinitySymbol, NumberFormatInfo::NegativeInfinitySymbol, or NumberFormatInfo::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 a IFormatProvider implementation, such as a NumberFormatInfo or CultureInfo object. The provider parameter supplies culture-specific information used in parsing. If provider is null or a NumberFormatInfo object cannot be obtained, the format information for the current culture is used.
The conversion fails if the s parameter is null or not a numeric value, the provider parameter does not yield a NumberFormatInfo object, or the style parameter is not a combination of bit flags from the NumberStyles enumeration.
Ordinarily, if you pass the Double::TryParse 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.
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.
Available since 4.5
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Available since 8.1