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Convert.ToInt32 Method (String)

.NET Framework 1.1

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

[Visual Basic]
Overloads Public Shared Function ToInt32( _
   ByVal value As String _
) As Integer
[C#]
public static int ToInt32(
 string value
);
[C++]
public: static int ToInt32(
 String* value
);
[JScript]
public static function ToInt32(
   value : String
) : int;

Parameters

value
A String containing a number to convert.

Return Value

A 32-bit signed integer equivalent to the value of value.

-or-

Zero if value is a null reference (Nothing in Visual Basic).

Exceptions

Exception Type 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.

Example

[Visual Basic, C#, C++] The following code example converts String representations of Int32 (32-bit integers) with the ToInt32 method, using default formatting.

[Visual Basic] 
' Example of the Convert.ToInt32( String ) and 
' Convert.ToInt32( String, IFormatProvider ) methods.
Imports System
Imports System.Globalization
Imports Microsoft.VisualBasic

Module ToInt32ProviderDemo

    Dim format As String = "{0,-20}{1,-20}{2}"

    ' Get the exception type name; remove the namespace prefix.
    Function GetExceptionType( ex As Exception ) As String

        Dim exceptionType   As String = ex.GetType( ).ToString( )
        Return exceptionType.Substring( _
            exceptionType.LastIndexOf( "."c ) + 1 )
    End Function

    Sub ConvertToInt32( numericStr As String, _
        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

        Console.WriteLine( format, numericStr, _
            defaultValue, providerValue )
    End Sub

    Sub Main( )

        ' 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

        Console.WriteLine( "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 )
        Console.WriteLine( format, "String to convert", _
            "Default/exception", "Provider/exception" )
        Console.WriteLine( format, "-----------------", _
            "-----------------", "------------------" )

        ' Convert strings, with and without an IFormatProvider.
        ConvertToInt32( "123456789", provider )
        ConvertToInt32( "+123456789", provider )
        ConvertToInt32( "pos 123456789", provider )
        ConvertToInt32( "-123456789", provider )
        ConvertToInt32( "neg 123456789", provider )
        ConvertToInt32( "123456789.", provider )
        ConvertToInt32( "123,456,789", provider )
        ConvertToInt32( "(123456789)", provider )
        ConvertToInt32( "2147483648", provider )
        ConvertToInt32( "-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

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

class ToInt32ProviderDemo
{
    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( 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 );
        }

        Console.WriteLine( format, numericStr, 
            defaultValue, providerValue );
    }

    public static void Main( )
    {
        // 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;

        Console.WriteLine("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" );
        Console.WriteLine( format, "String to convert", 
            "Default/exception", "Provider/exception" );
        Console.WriteLine( format, "-----------------", 
            "-----------------", "------------------" );

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

[C++] 
// Example of the Convert::ToInt32( String* ) and 
// Convert::ToInt32( String*, IFormatProvider* ) methods.
#using <mscorlib.dll>
using namespace System;
using namespace System::Globalization;

const __wchar_t* protoFmt = L"{0,-20}{1,-20}{2}" ;

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

void ConvertToInt32( String* numericStr, IFormatProvider* provider )
{
    Object* defaultValue;
    Object* providerValue;

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

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

    Console::WriteLine( new String( protoFmt ), numericStr, 
        defaultValue, providerValue );
}

void main( )
{
    // 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 = S"neg ";
    provider->PositiveSign = S"pos ";

    // These properties do not affect the conversion.
    // The input string cannot have decimal and group separators.
    provider->NumberDecimalSeparator = S".";
    provider->NumberGroupSeparator = S",";
    Int32 sizes __gc [ ] = { 3 };
    provider->NumberGroupSizes = sizes;
    provider->NumberNegativePattern = 0;

    Console::WriteLine(S"This example of\n" 
        S"  Convert::ToInt32( String* ) and \n" 
        S"  Convert::ToInt32( String*, IFormatProvider* ) " 
        S"\ngenerates the following output. It converts " 
        S"several strings to \nint values, using " 
        S"default formatting or a NumberFormatInfo object.\n" );
    Console::WriteLine( new String( protoFmt ), S"String to convert", 
        S"Default/exception", S"Provider/exception" );
    Console::WriteLine( new String( protoFmt ), S"-----------------", 
        S"-----------------", S"------------------" );

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

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

See Also

Convert Class | Convert Members | System Namespace | Convert.ToInt32 Overload List

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