UnmanagedMemoryStream.Length Propriedade

Definição

Obtém o comprimento dos dados em um fluxo.Gets the length of the data in a stream.

public:
 virtual property long Length { long get(); };
public override long Length { get; }
member this.Length : int64
Public Overrides ReadOnly Property Length As Long

Valor da propriedade

O comprimento dos dados no fluxo.The length of the data in the stream.

Exceções

O fluxo está fechado.The stream is closed.

Exemplos

O exemplo de código a seguir demonstra como ler e gravar na memória não gerenciada usando a UnmanagedMemoryStream classe.The following code example demonstrates how to read from and write to unmanaged memory using the UnmanagedMemoryStream class. Um bloco de memória não gerenciada é alocado e desalocado usando a Marshal classe.A block of unmanaged memory is allocated and de-allocated using the Marshal class.

// 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));
    }
}

Comentários

Se não alterado desde que o fluxo foi inicializado, essa propriedade retornará o valor de comprimento fornecido ao construtor.If unchanged since the stream was initialized, this property returns the length value provided to the constructor. Se ocorrerem alterações no fluxo, essa propriedade refletirá todas as alterações no comprimento dos dados.If changes to the stream have occurred, this property reflects any changes to the length of the data.

Aplica-se a