ICustomFormatter.Format(String, Object, IFormatProvider) ICustomFormatter.Format(String, Object, IFormatProvider) ICustomFormatter.Format(String, Object, IFormatProvider) ICustomFormatter.Format(String, Object, IFormatProvider) Method

定義

指定した書式およびカルチャ固有の書式情報を使用して、指定したオブジェクトの値をそれと等価な文字列形式に変換します。Converts the value of a specified object to an equivalent string representation using specified format and culture-specific formatting information.

public:
 System::String ^ Format(System::String ^ format, System::Object ^ arg, IFormatProvider ^ formatProvider);
public string Format (string format, object arg, IFormatProvider formatProvider);
abstract member Format : string * obj * IFormatProvider -> string
Public Function Format (format As String, arg As Object, formatProvider As IFormatProvider) As String

パラメーター

format
String String String String

書式指定を格納している書式指定文字列。A format string containing formatting specifications.

arg
Object Object Object Object

書式指定するオブジェクト。An object to format.

formatProvider
IFormatProvider IFormatProvider IFormatProvider IFormatProvider

現在のインスタンスについての書式情報を提供するオブジェクト。An object that supplies format information about the current instance.

戻り値

argformat の指定に従って書式指定した formatProvider の値の文字列形式。The string representation of the value of arg, formatted as specified by format and formatProvider.

次の例でICustomFormatterは、を実装して、整数値のバイナリ、8進数、および16進数の書式設定を許可しています。The following example implements ICustomFormatter to allow binary, octal, and hexadecimal formatting of integral values. この実装では、format パラメーターが、サポートされている3つの書式指定文字列 (バイナリの "B"、8進数の "O"、16進数の " arg H") のいずれかであるかどうかを判断し、パラメーターを適切に書式設定します。 ICustomFormatter.FormatIts ICustomFormatter.Format implementation determines whether the format parameter is one of the three supported format strings ("B" for binary, "O" for octal, and "H" for hexadecimal) and formats the arg parameter appropriately. それ以外のarg場合、 nullがでない場合argは、 IFormattable.ToStringパラメーターの実装 (存在する場合)、 ToStringまたはパラメーターなしのメソッド (存在しない場合) を呼び出します。Otherwise, if arg is not null, it calls the arg parameter's IFormattable.ToString implementation, if one exists, or its parameterless ToString method, if one does not. argnull の場合、メソッドは String.Empty を返します。If arg is null, the method returns String.Empty.

using System;
using System.Globalization;
using System.Numerics;

public class BinaryFormatter : IFormatProvider, ICustomFormatter
{
   // IFormatProvider.GetFormat implementation.
   public object GetFormat(Type formatType)
   {
      // Determine whether custom formatting object is requested.
      if (formatType == typeof(ICustomFormatter))
         return this;
      else
         return null;
   }   

   // Format number in binary (B), octal (O), or hexadecimal (H).
   public string Format(string format, object arg, IFormatProvider formatProvider)
   {
      // Handle format string.
      int baseNumber;
      // Handle null or empty format string, string with precision specifier.
      string thisFmt = String.Empty;
      // Extract first character of format string (precision specifiers
      // are not supported).
      if (! String.IsNullOrEmpty(format))
         thisFmt = format.Length > 1 ? format.Substring(0, 1) : format;
         

      // Get a byte array representing the numeric value.
      byte[] bytes;
      if (arg is sbyte)
      {
         string byteString = ((sbyte) arg).ToString("X2");
         bytes = new byte[1] { Byte.Parse(byteString, System.Globalization.NumberStyles.HexNumber ) };
      }
      else if (arg is byte) {
         bytes = new byte[1] { (byte) arg };
      }   
      else if (arg is short) {
         bytes = BitConverter.GetBytes((short) arg);
      }   
      else if (arg is int) {
         bytes = BitConverter.GetBytes((int) arg);
      }   
      else if (arg is long) {
         bytes = BitConverter.GetBytes((long) arg);
      }
      else if (arg is ushort) {
         bytes = BitConverter.GetBytes((ushort) arg);
      }
      else if (arg is uint) {
         bytes = BitConverter.GetBytes((uint) arg);
      }
      else if (arg is ulong) {
         bytes = BitConverter.GetBytes((ulong) arg);                  
      }
      else if (arg is BigInteger) {
         bytes = ((BigInteger) arg).ToByteArray();
      }
      else {
         try {
            return HandleOtherFormats(format, arg); 
         }
         catch (FormatException e) {
            throw new FormatException(String.Format("The format of '{0}' is invalid.", format), e);
         }
      }

      switch (thisFmt.ToUpper())
      {
         // Binary formatting.
         case "B":
            baseNumber = 2;
            break;        
         case "O":
            baseNumber = 8;
            break;
         case "H":
            baseNumber = 16;
            break;
         // Handle unsupported format strings.
         default:
         try {
            return HandleOtherFormats(format, arg); 
         }
         catch (FormatException e) {
            throw new FormatException(String.Format("The format of '{0}' is invalid.", format), e);
         }
      }
   
      // Return a formatted string.
      string numericString = String.Empty;
      for (int ctr = bytes.GetUpperBound(0); ctr >= bytes.GetLowerBound(0); ctr--)
      {
         string byteString = Convert.ToString(bytes[ctr], baseNumber);
         if (baseNumber == 2)
            byteString = new String('0', 8 - byteString.Length) + byteString;
         else if (baseNumber == 8)
            byteString = new String('0', 4 - byteString.Length) + byteString;
         // Base is 16.
         else     
            byteString = new String('0', 2 - byteString.Length) + byteString;

         numericString +=  byteString + " ";
      }
      return numericString.Trim();
   }

   private string HandleOtherFormats(string format, object arg)
   {
      if (arg is IFormattable) 
         return ((IFormattable)arg).ToString(format, CultureInfo.CurrentCulture);
      else if (arg != null)
         return arg.ToString();
      else
         return String.Empty;
   }
}
Imports System.Globalization
Imports System.Numerics

Public Class BinaryFormatter : Implements IFormatProvider, ICustomFormatter
   ' IFormatProvider.GetFormat implementation.
   Public Function GetFormat(formatType As Type) As Object _
                   Implements IFormatProvider.GetFormat
      ' Determine whether custom formatting object is requested.
      If formatType Is GetType(ICustomFormatter) Then
         Return Me
      Else
         Return Nothing
      End If
   End Function   

   ' Format number in binary (B), octal (O), or hexadecimal (H).
   Public Function Format(fmt As String, arg As Object, _
                          formatProvider As IFormatProvider) As String _
                   Implements ICustomFormatter.Format

     ' Handle format string.
      Dim base As Integer
      ' Handle null or empty format string, string with precision specifier.
      Dim thisFmt As String = String.Empty
      ' Extract first character of format string (precision specifiers
      ' are not supported by BinaryFormatter).
      If Not String.IsNullOrEmpty(fmt) Then
         thisFmt = CStr(IIf(fmt.Length > 1, fmt.Substring(0, 1), fmt))
      End If
         


      ' Get a byte array representing the numeric value.
      Dim bytes() As Byte
      If TypeOf(arg) Is SByte Then
         Dim byteString As String = CType(arg, SByte).ToString("X2")
         bytes = New Byte(0) { Byte.Parse(byteString, System.Globalization.NumberStyles.HexNumber ) }
      ElseIf TypeOf(arg) Is Byte Then
         bytes = New Byte(0) { CType(arg, Byte) }
      ElseIf TypeOf(arg) Is Int16 Then
         bytes = BitConverter.GetBytes(CType(arg, Int16))
      ElseIf TypeOf(arg) Is Int32 Then
         bytes = BitConverter.GetBytes(CType(arg, Int32))
      ElseIf TypeOf(arg) Is Int64 Then
         bytes = BitConverter.GetBytes(CType(arg, Int64))
      ElseIf TypeOf(arg) Is UInt16 Then
         bytes = BitConverter.GetBytes(CType(arg, UInt16))
      ElseIf TypeOf(arg) Is UInt32 Then
         bytes = BitConverter.GetBytes(CType(arg, UInt64))
      ElseIf TypeOf(arg) Is UInt64 Then
         bytes = BitConverter.GetBytes(CType(arg, UInt64))                  
      ElseIf TypeOf(arg) Is BigInteger Then
         bytes = CType(arg, BigInteger).ToByteArray()
      Else
         Try 
            Return HandleOtherFormats(fmt, arg) 
         Catch e As FormatException 
            Throw New FormatException(String.Format("The format of '{0}' is invalid.", fmt), e)
         End Try
      End If

      Select Case thisFmt.ToUpper()
         ' Binary formatting.
         Case "B"
            base = 2        
         Case "O"
            base = 8
         Case "H"
            base = 16
         ' Handle unsupported format strings.
         Case Else
            Try 
               Return HandleOtherFormats(fmt, arg) 
            Catch e As FormatException 
               Throw New FormatException(String.Format("The format of '{0}' is invalid.", fmt), e)
            End Try
      End Select
      
      ' Return a formatted string.
      Dim numericString As String = String.Empty
      For ctr As Integer = bytes.GetUpperBound(0) To bytes.GetLowerBound(0) Step -1
         Dim byteString As String = Convert.ToString(bytes(ctr), base)
         If base = 2 Then
            byteString = New String("0"c, 8 - byteString.Length) + byteString
         ElseIf base = 8 Then
            byteString = New String("0"c, 4 - byteString.Length) + byteString
         ' Base is 16.
         Else     
            byteString = New String("0"c, 2 - byteString.Length) + byteString
         End If
         numericString +=  byteString + " "
      Next
      Return numericString.Trim()
   End Function
   
   Private Function HandleOtherFormats(fmt As String, arg As Object) As String
      If TypeOf arg Is IFormattable Then
         Return DirectCast(arg, IFormattable).ToString(fmt, CultureInfo.CurrentCulture)
      ElseIf arg IsNot Nothing Then
         Return arg.ToString()
      Else
         Return String.Empty
      End If
   End Function
End Class

BinaryFormatter次の例に示すように、を使用しBinaryFormatterて、 Formatメソッドproviderのパラメーターとしてオブジェクトを渡すことにより、カスタム書式設定を提供できます。BinaryFormatter can then be used to provide custom formatting by passing a BinaryFormatter object as the provider parameter of the Format method, as the following example shows.

public class Example
{
   public static void Main()
   {
      Console.WindowWidth = 100;
      
      byte byteValue = 124;
      Console.WriteLine(String.Format(new BinaryFormatter(), 
                                      "{0} (binary: {0:B}) (hex: {0:H})", byteValue));
      
      int intValue = 23045;
      Console.WriteLine(String.Format(new BinaryFormatter(), 
                                      "{0} (binary: {0:B}) (hex: {0:H})", intValue));
      
      ulong ulngValue = 31906574882;
      Console.WriteLine(String.Format(new BinaryFormatter(), 
                                      "{0}\n   (binary: {0:B})\n   (hex: {0:H})", 
                                      ulngValue));

      BigInteger bigIntValue = BigInteger.Multiply(Int64.MaxValue, 2);
      Console.WriteLine(String.Format(new BinaryFormatter(), 
                                      "{0}\n   (binary: {0:B})\n   (hex: {0:H})", 
                                      bigIntValue));
   }
}
// The example displays the following output:
//    124 (binary: 01111100) (hex: 7c)
//    23045 (binary: 00000000 00000000 01011010 00000101) (hex: 00 00 5a 05)
//    31906574882
//       (binary: 00000000 00000000 00000000 00000111 01101101 11000111 10110010 00100010)
//       (hex: 00 00 00 07 6d c7 b2 22)
//    18446744073709551614
//       (binary: 00000000 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111110)
//       (hex: 00 ff ff ff ff ff ff ff fe)
Public Module Example
   Public Sub Main
      Console.WindowWidth = 100
      
      Dim byteValue As Byte = 124
      Console.WriteLine(String.Format(New BinaryFormatter(), _
                                      "{0} (binary: {0:B}) (hex: {0:H})", byteValue))
      
      Dim intValue As Integer = 23045
      Console.WriteLine(String.Format(New BinaryFormatter(), _
                                      "{0} (binary: {0:B}) (hex: {0:H})", intValue))
      
      Dim ulngValue As ULong = 31906574882
      Console.WriteLine(String.Format(New BinaryFormatter(), _
                                      "{0} {1}   (binary: {0:B}) {1}   (hex: {0:H})", _
                                      ulngValue, vbCrLf))

      Dim bigIntValue As BigInteger = BigInteger.Multiply(Int64.MaxValue, 2)
      Console.WriteLine(String.Format(New BinaryFormatter(), _
                                      "{0} {1}   (binary: {0:B}) {1}   (hex: {0:H})", _
                                      bigIntValue, vbCrLf))
   End Sub
End Module
' The example displays the following output:
'    124 (binary: 01111100) (hex: 7c)
'    23045 (binary: 00000000 00000000 01011010 00000101) (hex: 00 00 5a 05)
'    31906574882
'       (binary: 00000000 00000000 00000000 00000111 01101101 11000111 10110010 00100010)
'       (hex: 00 00 00 07 6d c7 b2 22)
'    18446744073709551614
'       (binary: 00000000 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111110)
'       (hex: 00 ff ff ff ff ff ff ff fe)

注釈

ICustomFormatter.Format はコールバック メソッドです。ICustomFormatter.Format is a callback method. またはString.Format(IFormatProvider, String, Object[]) StringBuilder.AppendFormat(IFormatProvider, String, Object[])などのカスタム書式設定をサポートするメソッドによって呼び出されます。It is called by a method that supports custom formatting, such as String.Format(IFormatProvider, String, Object[]) or StringBuilder.AppendFormat(IFormatProvider, String, Object[]). 実装は、複合書式指定文字列の書式指定項目ごとに1回呼び出されます。The implementation is called once for each format item in a composite format string. たとえば、次のステートメントICustomFormatter.Formatでは、メソッドが3回呼び出されます。For example, in the following statement, the ICustomFormatter.Format method is called three times.

Console.WriteLine(String.Format(new BinaryFormatter(), 
                                "{0} (binary: {0:B}) (hex: {0:H})", byteValue));
Console.WriteLine(String.Format(New BinaryFormatter(), _
                                "{0} (binary: {0:B}) (hex: {0:H})", byteValue))

argパラメーターは、オブジェクトリスト内のオブジェクトのうち、0から始まる位置が特定の書式項目のインデックスに対応するオブジェクトです。The arg parameter is the object in the object list whose zero-based position corresponds to the index of a particular format item.

パラメーター formatformatStringは、書式指定項目のコンポーネントである書式指定文字列が含まれています。The format parameter contains a format string, which is the formatString component of a format item. 書式指定項目にコンポーネントがformatStringない場合、のformat値はnullになります。If the format item has no formatString component, the value of format is null. formatnull場合、のarg種類によっては、任意の既定の書式指定を使用できる場合があります。If format is null, depending on the type of arg, you may be able to use the default format specification of your choice.

パラメーターは、のarg書式設定を提供するの実装です。IFormatProvider formatProviderThe formatProvider parameter is the IFormatProvider implementation that provides formatting for arg. 通常は、 ICustomFormatter実装のインスタンスです。Typically, it is an instance of your ICustomFormatter implementation. formatProvidernullの場合は、そのパラメーターを無視します。If formatProvider is null, ignore that parameter.

Formatメソッドの実装には次の機能が含まれている必要があるため、.NET Framework がサポートされていない書式設定を提供できます。Your implementation of the Format method must include the following functionality so the .NET Framework can provide formatting you do not support. 書式指定メソッドで形式がサポートされていない場合は、書式設定さIFormattableれているオブジェクトがインターフェイスを実装しているかどうかを確認します。If your format method does not support a format, determine whether the object being formatted implements the IFormattable interface. 存在する場合は、そのIFormattable.ToStringインターフェイスのメソッドを呼び出します。If it does, invoke the IFormattable.ToString method of that interface. それ以外の場合はObject.ToString 、基になるオブジェクトの既定のメソッドを呼び出します。Otherwise, invoke the default Object.ToString method of the underlying object. 次のコードは、このパターンを示しています。The following code illustrates this pattern.

if (arg is IFormattable) 
   return ((IFormattable)arg).ToString(format, CultureInfo.CurrentCulture);
else if (arg != null)
   return arg.ToString();
If TypeOf arg Is IFormattable Then
   Return DirectCast(arg, IFormattable).ToString(fmt, CultureInfo.CurrentCulture)
ElseIf arg IsNot Nothing Then
   Return arg.ToString()

適用対象

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