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  • Artykuł

Byte.Parse Method (String, NumberStyles)

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

Converts the string representation of a number in a specified style to its Byte equivalent.

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

Syntax

'Declaration
Public Shared Function Parse ( _
    s As String, _
    style As NumberStyles _
) As Byte

public static byte Parse(
    string s,
    NumberStyles style
)

Parameters

  • s
    Type: System.String
    A string containing a number to convert. The string is interpreted using the style specified by style.

Return Value

Type: System.Byte
The Byte value equivalent to the number contained in s.

Exceptions

Exception Condition
ArgumentNullException

s is nulla null reference (Nothing in Visual Basic).
FormatException

s is not of the correct format.
OverflowException

s represents a number less than Byte.MinValue or greater than Byte.MaxValue.

-or-

s includes non-zero fractional digits.
ArgumentException

style is not a NumberStyles value.

-or-

style is not a combination of NumberStyles.AllowHexSpecifier and NumberStyles.HexNumber values.

Remarks

The style parameter defines the style elements (such as white space or the positive sign) 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. Depending on the value of style, the s parameter may include the following elements:

[ws][$][sign]digits[.fractional_digits][e[sign]digits][ws]

Or, if style includes AllowHexSpecifier:

[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 beginning of s if style includes the NumberStyles.AllowLeadingWhite flag, or 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.CurrencyPositivePattern property of the current culture. The current culture's currency symbol can appear in s if style includes the NumberStyles.AllowCurrencySymbol flag.

sign

An optional positive sign. (The method throws an OverflowException if a negative sign is present in s.) The sign can appear at the beginning of s if style includes the NumberStyles.AllowLeadingSign flag, or at the end of s if style includes the NumberStyles.AllowTrailingSign flag.

digits

A sequence of digits from 0 through 9.

.

A culture-specific decimal point symbol. The current culture's decimal point symbol can appear in s if style includes the NumberStyles.AllowDecimalPoint flag.

fractional_digits

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

e

The e or E character, which indicates that the value is represented in exponential notation. The s 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 style) always parses successfully. Most of the remaining NumberStyles members control elements that may be 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 s.

Non-composite NumberStyles values

Elements permitted in s in addition to digits

NumberStyles.None

Decimal digits only.

NumberStyles.AllowDecimalPoint

The . and fractional_digits elements. However, fractional_digits must consist of only one or more 0 digits or an OverflowException is thrown.

NumberStyles.AllowExponent

The s parameter can also use exponential notation.

NumberStyles.AllowLeadingWhite

The ws element at the beginning of s.

NumberStyles.AllowTrailingWhite

The ws element at the end of s.

NumberStyles.AllowLeadingSign

A positive sign can appear before digits.

NumberStyles.AllowTrailingSign

A positive sign can appear after digits.

NumberStyles.AllowParentheses

Although this flag is supported, the use of parentheses in s results in an OverflowException.

NumberStyles.AllowThousands

Although the group separator symbol can appear in s, it can be preceded by only one or more 0 digits.

NumberStyles.AllowCurrencySymbol

The $ element.

If the NumberStyles.AllowHexSpecifier flag is used, s must be a hexadecimal value. The only other flags that can be combined with it are NumberStyles.AllowLeadingWhite and NumberStyles.AllowTrailingWhite. (The NumberStyles enumeration includes a composite number style, NumberStyles.HexNumber, that includes both white space flags.)

The s parameter is parsed using the formatting information in a NumberFormatInfo object that is initialized for the current system culture. To use the formatting information of some other culture, call the Byte.Parse(String, NumberStyles, IFormatProvider) overload.

Examples

The following example parses string representations of Byte values with the Byte.Parse(String, NumberStyles) method. The current culture for the example is en-US.

Dim value As String
Dim style As NumberStyles
Dim number As Byte

' Parse value with no styles allowed.
style = NumberStyles.None
value = " 241 "
Try
   number = Byte.Parse(value, style)
   outputBlock.Text &= String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf
Catch e As FormatException
   outputBlock.Text &= String.Format("Unable to parse '{0}'.", value) & vbCrLf
End Try

' Parse value with trailing sign.
style = NumberStyles.Integer Or NumberStyles.AllowTrailingSign
value = " 163+"
number = Byte.Parse(value, style)
outputBlock.Text &= String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf

' Parse value with leading sign.
value = "   +253  "
number = Byte.Parse(value, style)
outputBlock.Text &= String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf
' This example displays the following output:
'       Unable to parse ' 241 '.
'       Converted ' 163+' to 163.
'       Converted '   +253  ' to 253.            

string value;
NumberStyles style;
byte number;

// Parse value with no styles allowed.
style = NumberStyles.None;
value = " 241 ";
try
{
   number = Byte.Parse(value, style);
   outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";
}
catch (FormatException)
{
   outputBlock.Text += String.Format("Unable to parse '{0}'.", value) + "\n";
}

// Parse value with trailing sign.
style = NumberStyles.Integer | NumberStyles.AllowTrailingSign;
value = " 163+";
number = Byte.Parse(value, style);
outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";

// Parse value with leading sign.
value = "   +253  ";
number = Byte.Parse(value, style);
outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";
// This example displays the following output:
//       Unable to parse ' 241 '.
//       Converted ' 163+' to 163.
//       Converted '   +253  ' to 253.

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.