项目
11/17/2011

Int32.Parse Method (String, IFormatProvider)

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

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

Syntax

'Declaration
Public Shared Function Parse ( _
    s As String, _
    provider As IFormatProvider _
) As Integer

public static int Parse(
    string s,
    IFormatProvider provider
)

Parameters

s
Type: System.String
A string containing a number to convert.

provider
Type: System.IFormatProvider
An IFormatProvider that supplies culture-specific formatting information about s.

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).
FormatException	s is not of the correct format.
OverflowException	s represents a number less than MinValue or greater than MaxValue.

Remarks

This overload of the Parse(String, IFormatProvider) method is typically used to convert text that can be formatted in a variety of ways to an Int32 value. For example, it can be used to convert the text entered by a user into an HTML text box to a numeric value.

The s parameter contains a number of the form:

[ws][sign]digits[ws]

Items in square brackets ([ and ]) are optional. The following table describes each element.

Element	Description
ws	Optional white space.
sign	An optional sign.
digits	A sequence of digits ranging from 0 to 9.

The s parameter is interpreted using the NumberStyles.Integer style. In addition to decimal digits, only leading and trailing spaces together with a leading sign are allowed. To explicitly define the style elements that can be present in s, use the Int32.Parse(String, NumberStyles, IFormatProvider) method.

The provider parameter is an IFormatProvider implementation, such as a NumberFormatInfo or CultureInfo object. The provider parameter supplies culture-specific information about the format of s. If provider is nulla null reference (Nothing in Visual Basic), the NumberFormatInfo object for the current culture is used.

Examples

The following example illustrates the use of the Parse(String, IFormatProvider) method to parse a string. The method first attempts to parse the string using the current culture. If the parse operation fails, it attempts to parse the string using a neutral culture. If this parse operation fails, it attempts to parse the string using the invariant culture. Note that, in a real application, the Int32.TryParse(String, NumberStyles, IFormatProvider, Int32%) method is better suited for this purpose.

Public Function GetInteger(value As String) As Integer
   Dim culture As CultureInfo = Nothing
   Dim number As Integer

   ' Throw exception if string is empty.
   If String.IsNullOrEmpty(value) Then _
      Throw New ArgumentNullException("The input string is invalid.")

   ' Determine if value can be parsed using current culture.
   Try
      culture = CultureInfo.CurrentCulture
      number = Integer.Parse(value, culture)
      Return number
   Catch 
   End Try
   ' If Parse operation fails, see if there's a neutral culture.
   Try 
      culture = culture.Parent
      number = Integer.Parse(value, culture)
      Return number
   Catch 
   End Try
   ' If there is no neutral culture or if parse operation fails, use
   ' the invariant culture.
   culture = CultureInfo.InvariantCulture
   Try 
      number = Integer.Parse(value, culture)
      Return number
   ' All attempts to parse the string have failed; rethrow the exception.
   Catch e As FormatException
      Throw New FormatException(String.Format("Unable to parse '{0}'.", value), _ 
                                e)
   End Try
End Function

public static int GetInteger(string value)
{
   int number;
   CultureInfo culture = null;

   // Return if string is empty
   if (String.IsNullOrEmpty(value))
      throw new ArgumentNullException("The input string is invalid.");

   // Determine if value can be parsed using current culture.
   try
   {
      culture = CultureInfo.CurrentCulture;
      number = int.Parse(value, culture);
      return number;
   }
   catch {}
   // If Parse operation fails, see if there's a neutral culture.
   try {
      culture = culture.Parent;
      number = int.Parse(value, culture);
      return number;
   }   
   catch {}
   // If there is no neutral culture or if parse operation fails, use
   // the invariant culture.
   culture = CultureInfo.InvariantCulture;
   try {
      number = int.Parse(value, culture);
      return number;
   }
   // All attempts to parse the string have failed; rethrow the exception.
   catch (FormatException e)
   {
      throw new FormatException(String.Format("Unable to parse '{0}'.", value), 
                                e);
   }
}

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.

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