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Convert.ToInt32 Method (String)

Converts the specified String representation of a number to an equivalent 32-bit signed integer.

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

public static int ToInt32(
	string value
)

Parameters

value
Type: System.String
A String containing a number to convert.

Return Value

Type: System.Int32
A 32-bit signed integer equivalent to the value of value.
-or-
Zero if value is null.

ExceptionCondition
FormatException

value does not consist of an optional sign followed by a sequence of digits (zero through nine).

OverflowException

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

The return value is the result of invoking the Int32.Parse method on value.

If you prefer not to handle an exception if the conversion fails, you can call the Int32.TryParse method instead. It returns a Boolean value that indicates whether the conversion succeeded or failed.

The following code example converts String representations of 32-bit integers with the ToInt32 method, using default formatting.


// Example of the Convert.ToInt32( string ) and 
// Convert.ToInt32( string, IFormatProvider ) methods.
using System;
using System.Globalization;

class Example
{
   static string format = "{0,-20}{1,-20}{2}";

   // Get the exception type name; remove the namespace prefix.
   static string GetExceptionType(Exception ex)
   {
      string exceptionType = ex.GetType().ToString();
      return exceptionType.Substring(
          exceptionType.LastIndexOf('.') + 1);
   }

   static void ConvertToInt32(System.Windows.Controls.TextBlock outputBlock, string numericStr,
       IFormatProvider provider)
   {
      object defaultValue;
      object providerValue;

      // Convert numericStr to Int32 without a format provider.
      try
      {
         defaultValue = Convert.ToInt32(numericStr);
      }
      catch (Exception ex)
      {
         defaultValue = GetExceptionType(ex);
      }

      // Convert numericStr to Int32 with a format provider.
      try
      {
         providerValue = Convert.ToInt32(numericStr, provider);
      }
      catch (Exception ex)
      {
         providerValue = GetExceptionType(ex);
      }

      outputBlock.Text += String.Format(format, numericStr,
          defaultValue, providerValue) + "\n";
   }

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Create a NumberFormatInfo object and set several of its
      // properties that apply to numbers.
      NumberFormatInfo provider = new NumberFormatInfo();

      // These properties affect the conversion.
      provider.NegativeSign = "neg ";
      provider.PositiveSign = "pos ";

      // These properties do not affect the conversion.
      // The input string cannot have decimal and group separators.
      provider.NumberDecimalSeparator = ".";
      provider.NumberGroupSeparator = ",";
      provider.NumberGroupSizes = new int[] { 3 };
      provider.NumberNegativePattern = 0;

      outputBlock.Text += String.Format("This example of\n" +
          "  Convert.ToInt32( string ) and \n" +
          "  Convert.ToInt32( string, IFormatProvider ) " +
          "\ngenerates the following output. It converts " +
          "several strings to \nint values, using " +
          "default formatting or a NumberFormatInfo object.\n") + "\n";
      outputBlock.Text += String.Format(format, "String to convert",
          "Default/exception", "Provider/exception") + "\n";
      outputBlock.Text += String.Format(format, "-----------------",
          "-----------------", "------------------") + "\n";

      // Convert strings, with and without an IFormatProvider.
      ConvertToInt32(outputBlock, "123456789", provider);
      ConvertToInt32(outputBlock, "+123456789", provider);
      ConvertToInt32(outputBlock, "pos 123456789", provider);
      ConvertToInt32(outputBlock, "-123456789", provider);
      ConvertToInt32(outputBlock, "neg 123456789", provider);
      ConvertToInt32(outputBlock, "123456789.", provider);
      ConvertToInt32(outputBlock, "123,456,789", provider);
      ConvertToInt32(outputBlock, "(123456789)", provider);
      ConvertToInt32(outputBlock, "2147483648", provider);
      ConvertToInt32(outputBlock, "-2147483649", provider);
   }
}

/*
This example of
  Convert.ToInt32( string ) and
  Convert.ToInt32( string, IFormatProvider )
generates the following output. It converts several strings to
int values, using default formatting or a NumberFormatInfo object.

String to convert   Default/exception   Provider/exception
-----------------   -----------------   ------------------
123456789           123456789           123456789
+123456789          123456789           FormatException
pos 123456789       FormatException     123456789
-123456789          -123456789          FormatException
neg 123456789       FormatException     -123456789
123456789.          FormatException     FormatException
123,456,789         FormatException     FormatException
(123456789)         FormatException     FormatException
2147483648          OverflowException   OverflowException
-2147483649         OverflowException   FormatException
*/


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

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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