BigInteger::TryParse Method (String, NumberStyles, IFormatProvider, BigInteger%)
Tries to convert the string representation of a number in a specified style and culture-specific format to its BigInteger equivalent, and returns a value that indicates whether the conversion succeeded.
Assembly: System.Numerics (in System.Numerics.dll)
public: static bool TryParse( String^ value, NumberStyles style, IFormatProvider^ provider, [OutAttribute] BigInteger% result )
- Type: System::String
The string representation of a number. The string is interpreted using the style specified by style.
- Type: System.Globalization::NumberStyles
A bitwise combination of enumeration values that indicates the style elements that can be present in value. A typical value to specify is NumberStyles::Integer.
- Type: System::IFormatProvider
An object that supplies culture-specific formatting information about value.
- Type: System.Numerics::BigInteger%
When this method returns, contains the BigInteger equivalent to the number that is contained in value, or BigInteger::Zero if the conversion failed. The conversion fails if the value parameter is nullptr or is not in a format that is compliant with style. This parameter is passed uninitialized.
Return ValueType: System::Boolean
true if the value parameter was converted successfully; otherwise, false.
The method is like the Parse(String, NumberStyles, IFormatProvider) method, except that it does not throw an exception if the conversion fails. This method eliminates the need to use exception handling to test for a FormatException if value is invalid and cannot be parsed successfully.
The style parameter defines the style elements (such as white space or a positive or negative sign) that are allowed in the value parameter for the parse operation to succeed. It must be a combination of bit flags from the NumberStyles enumeration. Depending on the value of style, the value parameter may include the following elements:
If the style parameter includes AllowHexSpecifier, the value parameter may include the following elements:
Elements in square brackets ([ and ]) are optional. The following table describes each element.
Optional white space. White space can appear at the start of value if style includes the NumberStyles::AllowLeadingWhite flag, or at the end of value if style includes the NumberStyles::AllowTrailingWhite flag.
A culture-specific currency symbol. Its position in the string is defined by the CurrencyPositivePattern property of the NumberFormatInfo object returned by the GetFormat method of the provider parameter. The currency symbol can appear in value if style includes the NumberStyles::AllowCurrencySymbol flag.
An optional sign. The sign can appear at the start of value if style includes the NumberStyles::AllowLeadingSign flag, and it can appear at the end of value if style includes the NumberStyles::AllowTrailingSign flag. Parentheses can be used in value to indicate a negative value if style includes the NumberStyles::AllowParentheses flag.
A sequence of digits from 0 through 9.
A culture-specific group separator. The group separator of the culture specified by provider can appear in value if style includes the NumberStyles::AllowThousands flag.
A culture-specific decimal point symbol. The decimal point symbol of the culture specified by provider can appear in value if style includes the NumberStyles::AllowDecimalPoint flag.
One or more occurrences of the digit 0. Fractional digits can appear in value only if style includes the NumberStyles::AllowDecimalPoint flag.
The "e" or "E" character, which indicates that the value is represented in exponential (scientific) notation. The value parameter can represent a number in exponential notation if style includes the NumberStyles::AllowExponent flag.
A sequence of digits from 0 through 9. The value parameter can represent a number in exponential notation if style includes the NumberStyles::AllowExponent flag.
A sequence of hexadecimal digits from 0 through f, or 0 through F.
A string with decimal digits only (which corresponds to the NumberStyles::None flag) always parses successfully. Most of the remaining NumberStyles members control elements that may be present, but are not required to be present, in this input string. The following table indicates how individual NumberStyles members affect the elements that may be present in value.
Non-composite NumberStyles values
Elements permitted in value in addition to digits
Decimal digits only.
The decimal point (.) and fractional_digits elements. However, fractional_digits must consist of only one or more 0 digits, or the method returns false.
The "e" or "E" character, which indicates exponential notation, along with exponential_digits. If value represents a number in exponential notation, it cannot have a non-zero, fractional component.
The ws element at the start of value.
The ws element at the end of value.
The sign element before digits.
The sign element after digits.
The sign element in the form of parentheses enclosing the numeric value.
The group separator (,) element.
The currency ($) element.
All elements. However, value cannot represent a hexadecimal number or a number in exponential notation.
The ws element at the start or end of value, sign at the start of value, and the decimal point (.) symbol. The value parameter can also use exponential notation.
The ws, sign, group separator (,), and decimal point (.) elements.
All elements. However, value cannot represent a hexadecimal number.
If you use the TryParse method to round-trip the string representation of a BigInteger value that was output by the ToString method, you should use the BigInteger::ToString(String) method with the "R" format specifier to generate the string representation of the BigInteger value. Otherwise, the string representation of the BigInteger preserves only the 50 most significant digits of the original value, and data may be lost when you use the TryParse method to restore the BigInteger value.
If the NumberStyles::AllowHexSpecifier flag is used, value must be a hexadecimal value. The only other flags that can be present in style are NumberStyles::AllowLeadingWhite and NumberStyles::AllowTrailingWhite. (The NumberStyles enumeration has a composite style, HexNumber, that includes both white-space flags.)
If value is the string representation of a hexadecimal number, it cannot be preceded by any decoration (such as 0x or &h) that differentiates it as a hexadecimal number. This causes the conversion to fail.
If value is a hexadecimal string, the method interprets value as a negative number stored by using two's complement representation if its first two hexadecimal digits are greater than or equal to 0x80. In other words, the method interprets the highest-order bit of the first byte in value as the sign bit. To make sure that a hexadecimal string is correctly interpreted as a positive number, the first digit in value must have a value of zero. For example, the method interprets 0x80 as a negative value, but it interprets either 0x080 or 0x0080 as a positive value. The following example illustrates the difference between hexadecimal strings that represent negative and positive values.
The provider parameter is an IFormatProvider implementation. Its GetFormat method returns a NumberFormatInfo object that provides culture-specific information about the format of value. The provider parameter can be any one of the following:
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 NumberFormatInfo object for the current culture is used.
The following example makes some calls to the method using various combinations of values for the style and provider parameters.
A number of the individual calls to the method pass an instance of the following BigIntegerFormatProvider class, which defines a tilde (~) as the negative sign.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.