共用方式為

  • 發行項

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

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Tries to convert the string representation of a number in a specified style and culture-specific format to its SByte equivalent, and returns a value that indicates whether the conversion succeeded.

This API is not CLS-compliant. The CLS-compliant alternative is TryParse(String, Int16%).

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

Syntax

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

[CLSCompliantAttribute(false)]
public static bool TryParse(
    string s,
    NumberStyles style,
    IFormatProvider provider,
    out sbyte 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.SByte%
    When this method returns, contains the 8-bit signed integer value equivalent to the number 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, or represents a number less than MinValue or greater than MaxValue. 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 not a combination of AllowHexSpecifier and HexNumber values.

Remarks

The TryParse(String, NumberStyles, IFormatProvider, SByte%) 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:

[ws][$][sign][digits,]digits[.fractional_digits][E[sign]exponential_digits][ws]

If the style parameter includes AllowHexSpecifier, the value parameter may include the following elements:

[ws]hexdigits[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 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.

sign

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.

digits

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.

fractional_digits

One or more occurrences of the digit 0. Fractional digits can appear in value only if style includes the NumberStyles.AllowDecimalPoint flag.

E

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.

exponential_digits

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.

hexdigits

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

None

Decimal digits only.

AllowDecimalPoint

The decimal point (.) and fractional_digits elements. However, fractional_digits must consist of only one or more 0 digits, or the method returns false.

AllowExponent

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.

AllowLeadingWhite

The ws element at the start of value.

AllowTrailingWhite

The ws element at the end of value.

AllowLeadingSign

The sign element before digits.

AllowTrailingSign

The sign element after digits.

AllowParentheses

The sign element in the form of parentheses enclosing the numeric value.

AllowThousands

The group separator (,) element.

AllowCurrencySymbol

The currency ($) element.

Currency

All elements. However, value cannot represent a hexadecimal number or a number in exponential notation.

Float

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.

Number

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

Any

All elements. However, value cannot represent a hexadecimal number.

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.)

NoteNote:

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.

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:

If provider is nulla null reference (Nothing in Visual Basic), the NumberFormatInfo object for the current culture is used.

Examples

The following example calls the TryParse(String, NumberStyles, IFormatProvider, SByte%) method with a number of different string and NumberStyles values.

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.