Convert.ToInt32 Method (String)
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Converts the specified String representation of a number to an equivalent 32-bit signed integer.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Shared Function ToInt32 ( _
value As String _
) As Integer
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 nulla null reference (Nothing in Visual Basic).
Exceptions
| Exception | Condition |
|---|---|
| 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. |
Remarks
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.
Examples
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.
Imports System.Globalization
Module Example
Dim format As String = "{0,-20}{1,-20}{2}"
' Get the exception type name; remove the namespace prefix.
Function GetExceptionType(ByVal ex As Exception) As String
Dim exceptionType As String = ex.GetType().ToString()
Return exceptionType.Substring( _
exceptionType.LastIndexOf("."c) + 1)
End Function
Sub ConvertToInt32(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal numericStr As String, _
ByVal provider As IFormatProvider)
Dim defaultValue As Object
Dim providerValue As Object
' Convert numericStr to Int32 without a format provider.
Try
defaultValue = Convert.ToInt32(numericStr)
Catch ex As Exception
defaultValue = GetExceptionType(ex)
End Try
' Convert numericStr to Int32 with a format provider.
Try
providerValue = Convert.ToInt32(numericStr, provider)
Catch ex As Exception
providerValue = GetExceptionType(ex)
End Try
outputBlock.Text &= String.Format(format, numericStr, _
defaultValue, providerValue) & vbCrLf
End Sub
Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
' Create a NumberFormatInfo object and set several of its
' properties that apply to numbers.
Dim provider As NumberFormatInfo = 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 Integer() {3}
provider.NumberNegativePattern = 0
outputBlock.Text &= String.Format("This example of" & vbCrLf & _
" Convert.ToInt32( String ) and " & vbCrLf & _
" Convert.ToInt32( String, IFormatProvider ) " & _
vbCrLf & "generates the following output. It " & _
"converts several strings to " & vbCrLf & "Integer " & _
"values, using default formatting " & _
"or a NumberFormatInfo object." & vbCrLf) & vbCrLf
outputBlock.Text &= String.Format(format, "String to convert", _
"Default/exception", "Provider/exception") & vbCrLf
outputBlock.Text &= String.Format(format, "-----------------", _
"-----------------", "------------------") & vbCrLf
' 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)
End Sub
End Module
' This example of
' Convert.ToInt32( String ) and
' Convert.ToInt32( String, IFormatProvider )
' generates the following output. It converts several strings to
' Integer 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
// 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
*/
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.