撰寫資料流

發行項
08/12/2011

支援存放區為儲存媒體，例如磁碟或記憶體。各個不同的支援存放區都實作它自己的資料流做為 Stream 類別的實作。各個資料流類型都對它的指定支援存放區讀取並寫入位元組。連接至支援存放區的資料流稱為基底資料流。基底資料流擁有建構函式，其具備連接資料流至支援存放區的必要參數。例如，FileStream 具有指定路徑參數的建構函式，這參數可指定檔案將如何為處理序所共用，或諸如此類。

System.IO 類別的設計提供簡化的資料流撰寫方式。基底資料流可附加至一個或多個傳遞資料流，以提供想要的功能。讀取器或寫入器可附加至鏈結的結尾，以便能夠輕易讀取或寫入想要的型別。

下列程式碼範例針對現有的 MyFile.txt 建立 FileStream，以便緩衝 MyFile.txt (注意，預設的情況下，會緩衝 FileStream)。接下來，會建立 StreamReader 以從 FileStream 讀取字元，後者會傳遞至 StreamReader 做為其建構函式引數。 ReadLine 會讀取直到 Peek 再也找不到字元為止。

Imports System
Imports System.IO

Public Class CompBuf
    Private Const FILE_NAME As String = "MyFile.txt"

    Public Shared Sub Main()
        If Not File.Exists(FILE_NAME) Then
            Console.WriteLine("{0} does not exist!", FILE_NAME)
            Return
        End If
        Dim fsIn As new FileStream(FILE_NAME, FileMode.Open, _
            FileAccess.Read, FileShare.Read)
        ' Create an instance of StreamReader that can read
        ' characters from the FileStream.
        Using sr As New StreamReader(fsIn)
            Dim input As String
            ' While not at the end of the file, read lines from the file.
            While sr.Peek() > -1
                input = sr.ReadLine()
                Console.WriteLine(input)
            End While
        End Using
    End Sub
End Class

using System;
using System.IO;

public class CompBuf
{
    private const string FILE_NAME = "MyFile.txt";

    public static void Main()
    {
        if (!File.Exists(FILE_NAME))
        {
            Console.WriteLine("{0} does not exist!", FILE_NAME);
            return;
        }
        FileStream fsIn = new FileStream(FILE_NAME, FileMode.Open,
            FileAccess.Read, FileShare.Read);
        // Create an instance of StreamReader that can read
        // characters from the FileStream.
        using (StreamReader sr = new StreamReader(fsIn))
        {
            string input;
            // While not at the end of the file, read lines from the file.
            while (sr.Peek() > -1)
            {
                input = sr.ReadLine();
                Console.WriteLine(input);
            }
        }
    }
}

using namespace System;
using namespace System::IO;

public ref class CompBuf
{
private:
    static String^ FILE_NAME = "MyFile.txt";

public:
    static void Main()
    {
        if (!File::Exists(FILE_NAME))
        {
            Console::WriteLine("{0} does not exist!", FILE_NAME);
            return;
        }
        FileStream^ fsIn = gcnew FileStream(FILE_NAME, FileMode::Open,
            FileAccess::Read, FileShare::Read);
        // Create an instance of StreamReader that can read
        // characters from the FileStream.
        StreamReader^ sr = gcnew StreamReader(fsIn);
        String^ input;

        // While not at the end of the file, read lines from the file.
        while (sr->Peek() > -1)
        {
            input = sr->ReadLine();
            Console::WriteLine(input);
        }
        sr->Close();
    }
};

int main()
{
    CompBuf::Main();
}

下列程式碼範例針對現有的 MyFile.txt 建立 FileStream，以便緩衝 MyFile.txt (注意，預設的情況下，會緩衝 FileStream)。接下來，會建立 BinaryReader 以從 FileStream 讀取位元組，後者會傳遞至 BinaryReader 做為其建構函式引數。 ReadByte 會讀取直到 PeekChar 再也找不到位元組為止。

Imports System
Imports System.IO

Public Class ReadBuf
    Private Const FILE_NAME As String = "MyFile.txt"

    Public Shared Sub Main()
        If Not File.Exists(FILE_NAME) Then
            Console.WriteLine("{0} does not exist.", FILE_NAME)
            Return
        End If
        Dim f As New FileStream(FILE_NAME, FileMode.Open, _
            FileAccess.Read, FileShare.Read)
        ' Create an instance of BinaryReader that can
        ' read bytes from the FileStream.
        Using br As new BinaryReader(f)
            Dim input As Byte
            ' While not at the end of the file, read lines from the file.
            While br.PeekChar() > -1
                input = br.ReadByte()
                Console.WriteLine (input)
            End While
        End Using
    End Sub
End Class

using System;
using System.IO;

public class ReadBuf
{
    private const string FILE_NAME = "MyFile.txt";

    public static void Main()
    {
        if (!File.Exists(FILE_NAME))
        {
            Console.WriteLine("{0} does not exist.", FILE_NAME);
            return;
        }
        FileStream f = new FileStream(FILE_NAME, FileMode.Open,
            FileAccess.Read, FileShare.Read);
        // Create an instance of BinaryReader that can
        // read bytes from the FileStream.
        using (BinaryReader br = new BinaryReader(f))
        {
            byte input;
            // While not at the end of the file, read lines from the file.
            while (br.PeekChar() > -1 )
            {
                input = br.ReadByte();
                Console.WriteLine(input);
            }
        }
    }
}

using namespace System;
using namespace System::IO;

public ref class ReadBuf
{
private:
    static String^ FILE_NAME = "MyFile.txt";

public:
    static void Main()
    {
        if (!File::Exists(FILE_NAME))
        {
            Console::WriteLine("{0} does not exist.", FILE_NAME);
            return;
        }
        FileStream^ f = gcnew FileStream(FILE_NAME, FileMode::Open,
            FileAccess::Read, FileShare::Read);
        // Create an instance of BinaryReader that can
        // read bytes from the FileStream.
        BinaryReader^ br = gcnew BinaryReader(f);
        Byte input;
        // While not at the end of the file, read lines from the file.
        while (br->PeekChar() >-1 )
        {
            input = br->ReadByte();
            Console::WriteLine(input);
        }
        br->Close();
    }
};

int main()
{
    ReadBuf::Main();
}