Convert.ToInt32 方法 (String) (System)

将数字的指定 String 表示形式转换为等效的 32 位有符号整数。

命名空间:System
程序集:mscorlib(在 mscorlib.dll 中)

语法

Visual Basic(声明)
Public Shared Function ToInt32 ( _
	value As String _
) As Integer
Visual Basic(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

参数

value

包含要转换的数字的 String

返回值

value 的值等效的 32 位有符号整数。 - 或 - 如果 value 为 空引用(在 Visual Basic 中为 Nothing),则为零。

异常

异常类型条件

FormatException

value 不是由一个可选符号后跟数字序列(0 到 9)组成的。

OverflowException

value 表示小于 MinValue 或大于 MaxValue 的数字。

备注

返回值是对 value 调用 Int32.Parse 方法的结果。

示例

下面的代码示例使用 ToInt32 方法,通过默认格式设置转换 32 位整数的 String 表示形式。

Visual Basic 复制代码
' 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# 复制代码
// 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++ 复制代码
// 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# 复制代码
// 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
*/

平台

Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表,请参见系统要求

版本信息

.NET Framework

受以下版本支持:2.0、1.1、1.0

.NET Compact Framework

受以下版本支持:2.0、1.0

请参见

参考

Convert 类
Convert 成员
System 命名空间