• Article

Int32.TryParse Method (String, NumberStyles, IFormatProvider, Int32%)

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Converts the string representation of a number in a specified style and culture-specific format to its 32-bit signed integer equivalent. A return value indicates whether the conversion succeeded.

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

Syntax

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

public static bool TryParse(
    string s,
    NumberStyles style,
    IFormatProvider provider,
    out int result
)

Parameters

  • s
    Type: System.String
    A string containing a number to convert. The string is interpreted using the style specified by style.
  • provider
    Type: System.IFormatProvider
    An object that supplies culture-specific formatting information about s.
  • result
    Type: System.Int32%
    When this method returns, contains the 32-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 method is like the Parse method, except the TryParse method does not throw an exception if the conversion fails. It eliminates the need to use exception handling to test for a FormatException in the event that s 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 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]digits][ws]

Or, if the style parameter 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, 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 CurrencyPositivePattern property of the NumberFormatInfo object returned by the GetFormat method of the provider parameter. The currency symbol can appear in s if style includes the NumberStyles.AllowCurrencySymbol flag.

sign

An optional sign. A sign symbol can appear in s if style includes the NumberStyles.AllowLeadingSign or NumberStyles.AllowTrailingSign flags.

digits

A sequence of digits from 0 through 9.

,

A culture-specific thousands separator. The thousands separator of the culture specified by provider can appear in s 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 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 flag) 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 decimal point (.) and fractional_digits elements. However, fractional_digits must consist of only one or more 0 digits or the method returns false.

NumberStyles.AllowExponent

The s parameter can also use exponential notation. If s represents a number in exponential notation, it must represent an integer within the range of the Int32 data type without a non-zero, fractional component.

NumberStyles.AllowLeadingWhite

The ws element at the beginning of s.

NumberStyles.AllowTrailingWhite

The ws element at the end of s.

NumberStyles.AllowLeadingSign

A sign can appear before digits.

NumberStyles.AllowTrailingSign

A sign can appear after digits.

NumberStyles.AllowParentheses

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

NumberStyles.AllowThousands

The thousands separator (,) element.

NumberStyles.AllowCurrencySymbol

The $ element.

NumberStyles.Currency

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

NumberStyles.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.

NumberStyles.Number

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

NumberStyles.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 present in style are NumberStyles.AllowLeadingWhite and NumberStyles.AllowTrailingWhite. (The NumberStyles enumeration has a composite style, NumberStyles.HexNumber, that includes both white space flags.)

The provider parameter is an IFormatProvider implementation, such as a CultureInfo object or a NumberFormatInfo object, whose GetFormat method returns a NumberFormatInfo object. The NumberFormatInfo object provides 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 calls the Int32.TryParse(String, NumberStyles, IFormatProvider, Int32%) method with a number of different string and NumberStyles values.

Imports System.Globalization

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim numericString As String
      Dim styles As NumberStyles

      numericString = "106779"
      styles = NumberStyles.Integer
      CallTryParse(outputBlock, numericString, styles)

      numericString = "-30677"
      styles = NumberStyles.None
      CallTryParse(outputBlock, numericString, styles)

      styles = NumberStyles.AllowLeadingSign
      CallTryParse(outputBlock, numericString, styles)

      numericString = "301677-"
      CallTryParse(outputBlock, numericString, styles)

      styles = styles Or NumberStyles.AllowTrailingSign
      CallTryParse(outputBlock, numericString, styles)

      numericString = "$10634"
      styles = NumberStyles.Integer
      CallTryParse(outputBlock, numericString, styles)

      styles = NumberStyles.Integer Or NumberStyles.AllowCurrencySymbol
      CallTryParse(outputBlock, numericString, styles)

      numericString = "10345.00"
      styles = NumberStyles.Integer Or NumberStyles.AllowDecimalPoint
      CallTryParse(outputBlock, numericString, styles)

      numericString = "10345.72"
      styles = NumberStyles.Integer Or NumberStyles.AllowDecimalPoint
      CallTryParse(outputBlock, numericString, styles)

      numericString = "22,593"
      styles = NumberStyles.Integer Or NumberStyles.AllowThousands
      CallTryParse(outputBlock, numericString, styles)

      numericString = "12E-01"
      styles = NumberStyles.Integer Or NumberStyles.AllowExponent
      CallTryParse(outputBlock, numericString, styles)

      numericString = "12E03"
      CallTryParse(outputBlock, numericString, styles)

      numericString = "80c1"
      CallTryParse(outputBlock, numericString, NumberStyles.HexNumber)

      numericString = "0x80C1"
      CallTryParse(outputBlock, numericString, NumberStyles.HexNumber)
   End Sub

   Private Sub CallTryParse(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal stringToConvert As String, ByVal styles As NumberStyles)
      Dim number As Integer
      Dim provider As CultureInfo

      ' If currency symbol is allowed, use en-US culture.
      If CBool(styles And NumberStyles.AllowCurrencySymbol) Then
         provider = CultureInfo.CurrentCulture
      Else
         provider = New CultureInfo("en-US")
      End If

      Dim result As Boolean = Int32.TryParse(stringToConvert, styles, _
                                             provider, number)
      If result Then
         outputBlock.Text += String.Format("Converted '{0}' to {1}.", stringToConvert, number) & vbCrLf
      Else
         outputBlock.Text += String.Format("Attempted conversion of '{0}' failed.", _
                           Convert.ToString(stringToConvert)) & vbCrLf
      End If
   End Sub
End Module
' The example displays the following output:
'       Converted '106779' to 106779.
'       Attempted conversion of '-30677' failed.
'       Converted '-30677' to -30677.
'       Attempted conversion of '301677-' failed.
'       Converted '301677-' to -301677.
'       Attempted conversion of '$10634' failed.
'       Converted '$10634' to 10634.
'       Converted '10345.00' to 10345.
'       Attempted conversion of '10345.72' failed.
'       Converted '22,593' to 22593.
'       Attempted conversion of '12E-01' failed.
'       Converted '12E03' to 12000.
'       Converted '80c1' to 32961.
'       Attempted conversion of '0x80C1' failed.

using System;
using System.Globalization;

public class Example
{
   private static System.Windows.Controls.TextBlock outputBlock;

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Example.outputBlock = outputBlock;

      string numericString;
      NumberStyles styles;

      numericString = "106779";
      styles = NumberStyles.Integer;
      CallTryParse(numericString, styles);

      numericString = "-30677";
      styles = NumberStyles.None;
      CallTryParse(numericString, styles);

      styles = NumberStyles.AllowLeadingSign;
      CallTryParse(numericString, styles);

      numericString = "301677-";
      CallTryParse(numericString, styles);

      styles = styles | NumberStyles.AllowTrailingSign;
      CallTryParse(numericString, styles);

      numericString = "$10634";
      styles = NumberStyles.Integer;
      CallTryParse(numericString, styles);

      styles = NumberStyles.Integer | NumberStyles.AllowCurrencySymbol;
      CallTryParse(numericString, styles);

      numericString = "10345.00";
      styles = NumberStyles.Integer | NumberStyles.AllowDecimalPoint;
      CallTryParse(numericString, styles);

      numericString = "10345.72";
      styles = NumberStyles.Integer | NumberStyles.AllowDecimalPoint;
      CallTryParse(numericString, styles);

      numericString = "22,593";
      styles = NumberStyles.Integer | NumberStyles.AllowThousands;
      CallTryParse(numericString, styles);

      numericString = "12E-01";
      styles = NumberStyles.Integer | NumberStyles.AllowExponent;
      CallTryParse(numericString, styles);

      numericString = "12E03";
      CallTryParse(numericString, styles);

      numericString = "80c1";
      CallTryParse(numericString, NumberStyles.HexNumber);

      numericString = "0x80C1";
      CallTryParse(numericString, NumberStyles.HexNumber);
   }

   private static void CallTryParse(string stringToConvert, NumberStyles styles)
   {
      int number;
      CultureInfo provider;

      // If currency symbol is allowed, use en-US culture.
      if ((styles & NumberStyles.AllowCurrencySymbol) > 0)
         provider = new CultureInfo("en-US");
      else
         provider = CultureInfo.InvariantCulture;

      bool result = Int32.TryParse(stringToConvert, styles,
                                   provider, out number);
      if (result)
         outputBlock.Text += String.Format("Converted '{0}' to {1}.", stringToConvert, number) + "\n";
      else
         outputBlock.Text += String.Format("Attempted conversion of '{0}' failed.",
                           Convert.ToString(stringToConvert)) + "\n";
   }
}
// The example displays the following output:
//       Converted '106779' to 106779.
//       Attempted conversion of '-30677' failed.
//       Converted '-30677' to -30677.
//       Attempted conversion of '301677-' failed.
//       Converted '301677-' to -301677.
//       Attempted conversion of '$10634' failed.
//       Converted '$10634' to 10634.
//       Converted '10345.00' to 10345.
//       Attempted conversion of '10345.72' failed.
//       Converted '22,593' to 22593.
//       Attempted conversion of '12E-01' failed.
//       Converted '12E03' to 12000.
//       Converted '80c1' to 32961.
//       Attempted conversion of '0x80C1' failed.

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.