.NET Framework クラス ライブラリ
Convert.ToInt32 メソッド (String)

指定した String 形式の数値を、それと等価な 32 ビット符号付き整数に変換します。

名前空間: System
アセンブリ: mscorlib (mscorlib.dll 内)

構文

Visual Basic (宣言)
Public Shared Function ToInt32 ( _
    value As String _
) As Integer
Visual Basic (使用法)
Dim value As String
Dim returnValue As Integer

returnValue = Convert.ToInt32(value)
C#
public static int ToInt32 (
    string value
)
C++
public:
static int ToInt32 (
    String^ value
)
J#
public static int ToInt32 (
    String value
)
JScript
public static function ToInt32 (
    value : String
) : int

パラメータ

value

変換する数値を格納している String

戻り値

value の値と等価な 32 ビット符号付き整数。 または value が null 参照 (Visual Basic では Nothing) の場合は 0。
例外

例外の種類条件

FormatException

value の構成が、省略可能な符号と、それに続く 0 から 9 までの一連の数字ではありません。

OverflowException

valueMinValue 未満の数値か、MaxValue より大きい数値を表しています。

解説

戻り値は、value に対して Int32.Parse メソッドを呼び出した結果得られる値です。

使用例

既定の書式設定を使用して、ToInt32 メソッドで String 形式の 32 ビット整数を変換するコード例を次に示します。

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 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 = 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( gcnew String( protoFmt ), numericStr, defaultValue, providerValue );
}

int main()
{
   
   // Create a NumberFormatInfo object and set several of its
   // properties that apply to numbers.
   NumberFormatInfo^ provider = gcnew 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 = ",";
   array<Int32>^sizes = {3};
   provider->NumberGroupSizes = sizes;
   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( gcnew String( protoFmt ), "String to convert", "Default/exception", "Provider/exception" );
   Console::WriteLine( gcnew String( protoFmt ), "-----------------", "-----------------", "------------------" );
   
   // 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
*/
J#
// Example of the Convert.ToInt32( string ) and 
// Convert.ToInt32( string, IFormatProvider ) methods.
import System.* ;
import System.Globalization.* ;

class ToInt32ProviderDemo
{
    private static String format = "{0,-20}{1,-20}{2}";   
   
    // Get the exception type name; remove the namespace prefix.
    static String GetExceptionType(System.Exception ex) 
    {
        String exceptionType = ex.GetType().ToString();
        return exceptionType.Substring((exceptionType.LastIndexOf('.') + 1)) ;
    } //GetExceptionType   
   
    static void ConvertToInt32(String numericStr, IFormatProvider provider) 
    {
        Object defaultValue;
        Object providerValue;
      
        // Convert numericStr to Int32 without a format provider.
        try {
            defaultValue = System.Convert.ToString(Convert.ToInt32(numericStr));
        }
        catch(System.Exception  ex) {      
            defaultValue = GetExceptionType(ex);
        }
      
        // Convert numericStr to Int32 with a format provider.
        try {
            providerValue = System.Convert.ToString(
                            Convert.ToInt32(numericStr, provider));
        }
        catch(System.Exception  ex) {      
            providerValue = GetExceptionType(ex);
        }
      
        Console.WriteLine(format, numericStr, defaultValue, providerValue);
     } //ConvertToInt32
      
    public static void main(String[] args)
    {
    
        // Create a NumberFormatInfo object and set several of its
        // properties that apply to numbers.
        NumberFormatInfo provider =  new NumberFormatInfo();
      
        // These properties affect the conversion.
        provider.set_NegativeSign("neg ");
        provider.set_PositiveSign("pos ");
      
        // These properties do not affect the conversion.
        // The input string cannot have decimal and group separators.
        provider.set_NumberDecimalSeparator(".");
        provider.set_NumberGroupSeparator(",");
        provider.set_NumberGroupSizes(new int[]{3});
        provider.set_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);
    } //main
} //ToInt32ProviderDemo

/*
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
*/
プラットフォーム

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework

サポート対象 : 2.0、1.1、1.0

.NET Compact Framework

サポート対象 : 2.0、1.0
参照

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