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  • Artykuł

Int32.Parse Method (String, NumberStyles)

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Converts the string representation of a number in a specified style to its 32-bit signed integer equivalent.

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

Syntax

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

public static int Parse(
    string s,
    NumberStyles style
)

Parameters

Return Value

Type: System.Int32
A 32-bit signed integer equivalent to the number specified in s.

Exceptions

Exception Condition
ArgumentNullException

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

style is not a NumberStyles value.

-or-

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

s is not in a format compliant with style.
OverflowException

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

-or-

s includes non-zero, fractional digits.

Remarks

The style parameter defines the style elements (such as white space, the positive or negative sign symbol, or the thousands separator symbol) 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,]digits[.fractional_digits][e[sign]exponential_digits][ws]

Or, if style includes AllowHexSpecifier:

[ws]hexdigits[ws]

Items 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, and 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 and NumberFormatInfo.CurrencyPositivePattern properties of the current culture. The current culture's currency symbol can appear in s if style includes the NumberStyles.AllowCurrencySymbol flag.

sign

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.

digits

fractional_digits

exponential_digits

A sequence of digits from 0 through 9. For fractional_digits, only the digit 0 is valid.

,

A culture-specific thousands separator symbol. The current culture's thousands separator 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. Only the digit 0 can appear as a fractional digit for the parse operation to succeed; if fractional_digits includes any other digit, an OverflowException is thrown.

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 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 the input string. The following table indicates how individual NumberStyles members affect the elements that may be present in s.

NumberStyles value

Elements permitted in s in addition to digits

None

The digits element only.

AllowDecimalPoint

The decimal point ( . ) and fractional-digits elements.

AllowExponent

The s parameter can also use exponential notation.

AllowLeadingWhite

The ws element at the beginning of s.

AllowTrailingWhite

The ws element at the end of s.

AllowLeadingSign

The sign element at the beginning of s.

AllowTrailingSign

The sign element at the end of s.

AllowParentheses

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

AllowThousands

The thousands separator ( , ) element.

AllowCurrencySymbol

The $ element.

Currency

All. The s parameter cannot represent a hexadecimal number or a number in exponential notation.

Float

The ws element at the beginning or end of s, sign at the beginning of s, and the decimal point ( . ) symbol. The s parameter can also use exponential notation.

Number

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

Any

All styles, except s cannot represent a hexadecimal number.

If the NumberStyles.AllowHexSpecifier flag is used, s must be a hexadecimal value. The only other flags that can be combined with the s parameter 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 specify the culture whose formatting information is used for the parse operation, call the Byte.Parse(String, NumberStyles, IFormatProvider) overload.

Examples

The following example uses the Int32.Parse(String, NumberStyles) method to parse the string representations of several Int32 values. The current culture for the example is en-US.

Imports System.Globalization

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Convert(outputBlock, "104.0", NumberStyles.AllowDecimalPoint)
      Convert(outputBlock, "104.9", NumberStyles.AllowDecimalPoint)
      Convert(outputBlock, " $17,198,064.42", NumberStyles.AllowCurrencySymbol Or _
                                 NumberStyles.Number)
      Convert(outputBlock, "103E06", NumberStyles.AllowExponent)
      Convert(outputBlock, "-1,345,791", NumberStyles.AllowThousands)
      Convert(outputBlock, "(1,345,791)", NumberStyles.AllowThousands Or _
                             NumberStyles.AllowParentheses)
   End Sub

   Private Sub Convert(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal value As String, ByVal style As NumberStyles)
      Try
         Dim number As Integer = Int32.Parse(value, style)
         outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) & vbCrLf
      Catch e As FormatException
         outputBlock.Text += String.Format("Unable to convert '{0}'.", value) & vbCrLf
      Catch e As OverflowException
         outputBlock.Text += String.Format("'{0}' is out of range of the Int32 type.", value) & vbCrLf
      End Try
   End Sub
End Module
' The example displays the following output:
'       Converted '104.0' to 104.
'       '104.9' is out of range of the Int32 type.
'       ' $17,198,064.42' is out of range of the Int32 type.
'       Converted '103E06' to 103000000.
'       Unable to convert '-1,345,791'.
'       Converted '(1,345,791)' to -1345791.

using System;
using System.Globalization;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Convert(outputBlock, "104.0", NumberStyles.AllowDecimalPoint);
      Convert(outputBlock, "104.9", NumberStyles.AllowDecimalPoint);
      Convert(outputBlock, " $17,198,064.42", NumberStyles.AllowCurrencySymbol |
                                 NumberStyles.Number);
      Convert(outputBlock, "103E06", NumberStyles.AllowExponent);
      Convert(outputBlock, "-1,345,791", NumberStyles.AllowThousands);
      Convert(outputBlock, "(1,345,791)", NumberStyles.AllowThousands |
                             NumberStyles.AllowParentheses);
   }

   private static void Convert(System.Windows.Controls.TextBlock outputBlock, string value, NumberStyles style)
   {
      try
      {
         int number = Int32.Parse(value, style);
         outputBlock.Text += String.Format("Converted '{0}' to {1}.", value, number) + "\n";
      }
      catch (FormatException)
      {
         outputBlock.Text += String.Format("Unable to convert '{0}'.", value) + "\n";
      }
      catch (OverflowException)
      {
         outputBlock.Text += String.Format("'{0}' is out of range of the Int32 type.", value) + "\n";
      }
   }
}
// The example displays the following output:
//       Converted '104.0' to 104.
//       '104.9' is out of range of the Int32 type.
//       ' $17,198,064.42' is out of range of the Int32 type.
//       Converted '103E06' to 103000000.
//       Unable to convert '-1,345,791'.
//       Converted '(1,345,791)' to -1345791.

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.