UnmanagedMemoryStream.Length Properti

Definisi

Ruang nama:

System.IO

Rakitan:

System.Runtime.dll

Sumber:

UnmanagedMemoryStream.cs

Mendapatkan panjang data dalam aliran.

public:
 virtual property long Length { long get(); };

public override long Length { get; }

member this.Length : int64

Public Overrides ReadOnly Property Length As Long

Nilai Properti

Int64

Panjang data dalam aliran.

Pengecualian

ObjectDisposedException

Aliran ditutup.

Contoh

Contoh kode berikut menunjukkan cara membaca dari dan menulis ke memori yang tidak dikelola menggunakan UnmanagedMemoryStream kelas . Blok memori yang tidak dikelola dialokasikan dan dibatalkan alokasinya Marshal menggunakan kelas .

// Note: You must compile this sample using the unsafe flag.
// From the command line, type the following: csc sample.cs /unsafe
using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

unsafe class Program
{
    static void Main()
    {
        // Create some data to write.
        byte[] text = UnicodeEncoding.Unicode.GetBytes("Data to write.");

        // Allocate a block of unmanaged memory.
        IntPtr memIntPtr = Marshal.AllocHGlobal(text.Length);

        // Get a byte pointer from the unmanaged memory block.
        byte* memBytePtr = (byte*)memIntPtr.ToPointer();

        UnmanagedMemoryStream writeStream =
            new UnmanagedMemoryStream(
            memBytePtr, text.Length, text.Length, FileAccess.Write);

        // Write the data.
        WriteToStream(writeStream, text);

        // Close the stream.
        writeStream.Close();

        // Create another UnmanagedMemoryStream for reading.
        UnmanagedMemoryStream readStream =
            new UnmanagedMemoryStream(memBytePtr, text.Length);

        // Display the contents of the stream to the console.
        PrintStream(readStream);

        // Close the reading stream.
        readStream.Close();

        // Free up the unmanaged memory.
        Marshal.FreeHGlobal(memIntPtr);
    }

    public static void WriteToStream(UnmanagedMemoryStream writeStream, byte[] text)
    {
        // Verify that the stream is writable:
        // By default, UnmanagedMemoryStream objects do not have write access,
        // write access must be set explicitly.
        if (writeStream.CanWrite)
        {
            // Write the data, byte by byte
            for (int i = 0; i < writeStream.Length; i++)
            {
                writeStream.WriteByte(text[i]);
            }
        }
    }

    public static void PrintStream(UnmanagedMemoryStream readStream)
    {
        byte[] text = new byte[readStream.Length];
        // Verify that the stream is writable:
        // By default, UnmanagedMemoryStream objects do not have write access,
        // write access must be set explicitly.
        if (readStream.CanRead)
        {
            // Write the data, byte by byte
            for (int i = 0; i < readStream.Length; i++)
            {
                text[i] = (byte)readStream.ReadByte();
            }
        }

        Console.WriteLine(UnicodeEncoding.Unicode.GetString(text));
    }
}

Keterangan

Jika tidak berubah sejak aliran diinisialisasi, properti ini mengembalikan nilai panjang yang diberikan kepada konstruktor. Jika perubahan pada aliran telah terjadi, properti ini mencerminkan perubahan apa pun pada panjang data.