UnmanagedMemoryStream.ReadByte Método

Definição

Lê um byte de um fluxo e avança a posição no fluxo em um byte ou retorna -1 caso esteja no final do fluxo.Reads a byte from a stream and advances the position within the stream by one byte, or returns -1 if at the end of the stream.

public:
 override int ReadByte();
public override int ReadByte ();
override this.ReadByte : unit -> int
Public Overrides Function ReadByte () As Integer

Retornos

O byte sem sinal é convertido em um objeto Int32 ou -1 se estiver no final do fluxo.The unsigned byte cast to an Int32 object, or -1 if at the end of the stream.

Exceções

O fluxo está fechado.The stream is closed.

A memória subjacente não dá suporte a leitura.The underlying memory does not support reading.

- ou --or-

A posição atual está no final do fluxo.The current position is at the end of the stream.

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. Neste exemplo, um UnmanagedMemoryStream objeto é passado para um método que verifica a CanRead propriedade antes de tentar ler e exibir o conteúdo para o console.In this example, an UnmanagedMemoryStream object is passed to a method which checks the CanRead property before attempting to read and display the contents to the console.

// 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

Use este método para retornar valores inteiros do fluxo.Use this method to return integer values from the stream.

Aplica-se a