BinaryReader.ReadChar 方法

定義

命名空間:

System.IO

組件:

System.Runtime.dll

來源:

BinaryReader.cs

按照所使用的 Encoding 和從資料流讀取的特定字元，自目前資料流讀取下一個字元，並將資料流中目前的位置往前移。

public:
 virtual char ReadChar();

public virtual char ReadChar ();

abstract member ReadChar : unit -> char
override this.ReadChar : unit -> char

Public Overridable Function ReadChar () As Char

傳回

Char

自目前資料流讀取的字元。

例外狀況

EndOfStreamException

已到達資料流的末端。

ObjectDisposedException

資料流已關閉。

IOException

發生 I/O 錯誤。

ArgumentException

讀取到 Surrogate 字元

範例

下列程式代碼範例示範如何使用記憶體作為備份存放區來讀取和寫入數據。

using namespace System;
using namespace System::IO;
int main()
{
   int i;
   array<Char>^invalidPathChars = Path::InvalidPathChars;
   MemoryStream^ memStream = gcnew MemoryStream;
   BinaryWriter^ binWriter = gcnew BinaryWriter( memStream );
   
   // Write to memory.
   binWriter->Write( "Invalid file path characters are: " );
   for ( i = 0; i < invalidPathChars->Length; i++ )
   {
      binWriter->Write( invalidPathChars[ i ] );

   }
   
   // Create the reader using the same MemoryStream 
   // as used with the writer.
   BinaryReader^ binReader = gcnew BinaryReader( memStream );
   
   // Set Position to the beginning of the stream.
   binReader->BaseStream->Position = 0;
   
   // Read the data from memory and write it to the console.
   Console::Write( binReader->ReadString() );
   array<Char>^memoryData = gcnew array<Char>(memStream->Length - memStream->Position);
   for ( i = 0; i < memoryData->Length; i++ )
   {
      memoryData[ i ] = binReader->ReadChar();

   }
   Console::WriteLine( memoryData );
}

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        int i = 0;
        char[] invalidPathChars = Path.InvalidPathChars;
        MemoryStream memStream = new MemoryStream();
        BinaryWriter binWriter = new BinaryWriter(memStream);

        // Write to memory.
        binWriter.Write("Invalid file path characters are: ");
        for(i = 0; i < invalidPathChars.Length; i++)
        {
            binWriter.Write(invalidPathChars[i]);
        }

        // Create the reader using the same MemoryStream
        // as used with the writer.
        BinaryReader binReader = new BinaryReader(memStream);

        // Set Position to the beginning of the stream.
        memStream.Position = 0;

        // Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString());
        char[] memoryData =
            new char[memStream.Length - memStream.Position];
        for(i = 0; i < memoryData.Length; i++)
        {
            memoryData[i] = binReader.ReadChar();
        }
        Console.WriteLine(memoryData);
    }
}

open System.IO

let invalidPathChars = Path.GetInvalidPathChars()
let memStream = new MemoryStream()
let binWriter = new BinaryWriter(memStream)

// Write to memory.
binWriter.Write "Invalid file path characters are: "
for i = 0 to invalidPathChars.Length - 1 do
    binWriter.Write invalidPathChars[i]

// Create the reader using the same MemoryStream
// as used with the writer.
let binReader = new BinaryReader(memStream)

// Set Position to the beginning of the stream.
memStream.Position <- 0

// Read the data from memory and write it to the console.
printf $"{binReader.ReadString()}"
let memoryData = Array.zeroCreate<char> (int (memStream.Length - memStream.Position))
for i = 0 to memoryData.Length - 1 do
    memoryData[i] <- binReader.ReadChar()
printfn $"{memoryData}"

Imports System.IO

Public Class BinaryRW

    Shared Sub Main()
    
        Dim i As Integer = 0
        Dim invalidPathChars() As Char = Path.InvalidPathChars
        Dim memStream As new MemoryStream()
        Dim binWriter As New BinaryWriter(memStream)

        ' Write to memory.
        binWriter.Write("Invalid file path characters are: ")
        For i = 0 To invalidPathChars.Length - 1
            binWriter.Write(invalidPathChars(i))
        Next i

        ' Create the reader using the same MemoryStream 
        ' as used with the writer.
        Dim binReader As New BinaryReader(memStream)

        ' Set Position to the beginning of the stream.
        memStream.Position = 0

        ' Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString())
        Dim memoryData( _
            CInt(memStream.Length - memStream.Position) - 1) As Char
        For i = 0 To memoryData.Length - 1
            memoryData(i) = binReader.ReadChar()
        Next i
        Console.WriteLine(memoryData)
    
    End Sub
End Class

備註

ReadChar如果方法嘗試讀取數據流中的 Surrogate 字元，則會引發例外狀況，而且數據流中的位置會前進。 如果數據流是可搜尋的，則會將位置還原至原始位置 ReadChar ，不過，如果數據流無法看見，則不會更正位置。 如果數據流中可以預期 Surrogate 字元，請改用 ReadChars 方法。

由於數據格式設定衝突，不建議使用此方法搭配下列編碼：

• UTF-7

• ISO-2022-JP

• ISCII

如需一般 I/O 工作的清單，請參閱 一般 I/O 工作。

另請參閱

• Encoding
• 檔案和資料流 I/O
• 作法：讀取檔案中的文字
• 作法：將文字寫入檔案