BinaryReader.ReadDouble BinaryReader.ReadDouble BinaryReader.ReadDouble BinaryReader.ReadDouble Method

定義

現在のストリームから 8 バイト浮動小数点値を読み取り、ストリームの現在位置を 8 バイトだけ進めます。Reads an 8-byte floating point value from the current stream and advances the current position of the stream by eight bytes.

public:
 virtual double ReadDouble();
public virtual double ReadDouble ();
abstract member ReadDouble : unit -> double
override this.ReadDouble : unit -> double
Public Overridable Function ReadDouble () As Double

戻り値

現在のストリームから読み取った 8 バイト浮動小数点値。An 8-byte floating point value read from the current stream.

例外

ストリームの末尾に到達しました。The end of the stream is reached.

ストリームは閉じられています。The stream is closed.

I/O エラーが発生しました。An I/O error occurred.

次のコード例では、MemoryStream クラスの上にある BinaryReader クラスと @no__t クラスを使用して、メモリに @no__t 0 データの読み取りと書き込みを行う方法を示します。The following code example shows how to read and write Double data to memory by using the BinaryReader and BinaryWriter classes on top of the MemoryStream class. MemoryStream は、Byte のデータのみを読み取りおよび書き込みます。MemoryStream only reads and writes Byte data.

using namespace System;
using namespace System::IO;
int main()
{
   int i;
   const int arrayLength = 1000;
   
   // Create random data to write to the stream.
   array<double>^dataArray = gcnew array<double>(arrayLength);
   Random^ randomGenerator = gcnew Random;
   for ( i = 0; i < arrayLength; i++ )
   {
      dataArray[ i ] = 100.1 * randomGenerator->NextDouble();

   }
   BinaryWriter^ binWriter = gcnew BinaryWriter( gcnew MemoryStream );
   try
   {
      
      // Write data to the stream.
      Console::WriteLine( "Writing data to the stream." );
      i = 0;
      for ( i = 0; i < arrayLength; i++ )
      {
         binWriter->Write( dataArray[ i ] );

      }
      
      // Create a reader using the stream from the writer.
      BinaryReader^ binReader = gcnew BinaryReader( binWriter->BaseStream );
      
      // Return to the beginning of the stream.
      binReader->BaseStream->Position = 0;
      try
      {
         
         // Read and verify the data.
         i = 0;
         Console::WriteLine( "Verifying the written data." );
         for ( i = 0; i < arrayLength; i++ )
         {
            if ( binReader->ReadDouble() != dataArray[ i ] )
            {
               Console::WriteLine( "Error writing data." );
               break;
            }

         }
         Console::WriteLine( "The data was written and verified." );
      }
      catch ( EndOfStreamException^ e ) 
      {
         Console::WriteLine( "Error writing data: {0}.", e->GetType()->Name );
      }

   }
   finally
   {
      binWriter->Close();
   }

}

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        int i;
        const int arrayLength = 1000;

        // Create random data to write to the stream.
        Random randomGenerator = new Random();
        double[] dataArray = new double[arrayLength];
        for(i = 0; i < arrayLength; i++)
        {
            dataArray[i] = 100.1 * randomGenerator.NextDouble();
        }

        using(BinaryWriter binWriter = 
            new BinaryWriter(new MemoryStream()))
        {
            // Write the data to the stream.
            Console.WriteLine("Writing data to the stream.");
            for(i = 0; i < arrayLength; i++)
            {
                binWriter.Write(dataArray[i]);
            }

            // Create a reader using the stream from the writer.
            using(BinaryReader binReader = 
                new BinaryReader(binWriter.BaseStream))
            {
                try
                {
                    // Return to the beginning of the stream.
                    binReader.BaseStream.Position = 0;

                    // Read and verify the data.
                    Console.WriteLine("Verifying the written data.");
                    for(i = 0; i < arrayLength; i++)
                    {
                        if(binReader.ReadDouble() != dataArray[i])
                        {
                            Console.WriteLine("Error writing data.");
                            break;
                        }
                    }
                    Console.WriteLine("The data was written " +
                        "and verified.");
                }
                catch(EndOfStreamException e)
                {
                    Console.WriteLine("Error writing data: {0}.",
                        e.GetType().Name);
                }
            }
        }
    }
}
Imports System.IO

Public Class BinaryRW

    Shared Sub Main()
    
        Dim i As Integer
        Const upperBound As Integer = 1000

        ' Create random data to write to the stream.
        Dim dataArray(upperBound) As Double
        Dim randomGenerator As New Random()
        For i = 0 To upperBound
            dataArray(i) = 100.1 * randomGenerator.NextDouble()
        Next i

        Dim binWriter As New BinaryWriter(New MemoryStream())
        Try

            ' Write data to the stream.
            Console.WriteLine("Writing data to the stream.")
            
            For i = 0 To upperBound
                binWriter.Write(dataArray(i))
            Next i

            ' Create a reader using the stream from the writer.
            Dim binReader As New BinaryReader(binWriter.BaseStream)

            ' Return to the beginning of the stream.
            binReader.BaseStream.Position = 0

            ' Read and verify the data.
            Try
                Console.WriteLine("Verifying the written data.")
                For i = 0 To upperBound
                    If binReader.ReadDouble() <> dataArray(i) Then
                        Console.WriteLine("Error writing data.")
                        Exit For
                    End If
                Next i
                Console.WriteLine("The data was written and verified.")
            Catch ex As EndOfStreamException
                Console.WriteLine("Error writing data: {0}.", _
                    ex.GetType().Name)
            End Try
        Finally
            binWriter.Close()
        End Try

    End Sub
End Class

注釈

BinaryReader は、読み取りに失敗した後にファイルの位置を復元しません。BinaryReader does not restore the file position after an unsuccessful read.

BinaryReader は、このデータ型をリトルエンディアン形式で読み取ります。BinaryReader reads this data type in little-endian format.

共通 I/O タスクの一覧は、 共通 I/O タスク を参照してください。For a list of common I/O tasks, see Common I/O Tasks.

適用対象

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