Marshal.WriteByte Method (IntPtr, Byte)

Writes a single byte value to unmanaged memory.

Namespace:  System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)

public static void WriteByte(
	IntPtr ptr,
	byte val
)

Parameters

ptr
Type: System.IntPtr

The address in unmanaged memory to write to.

val
Type: System.Byte

The value to write.

ExceptionCondition
AccessViolationException

ptr is not a recognized format.

-or-

ptr is null.

-or-

ptr is invalid.

WriteByte enables direct interaction with an unmanaged C-style byte array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before setting its element values.

The following example creates a block of unmanaged memory, writes a byte to the unmanaged memory, reads the byte back from unmanaged memory, and then disposes the unmanaged memory.

using System;
using System.Runtime.InteropServices;


namespace SecureStringExample
{

    class MarshalExample
    {


        static void Main(string[] args)
        {

            try
            {
                // Allocate 1 byte of unmanaged memory.
                IntPtr hGlobal = Marshal.AllocHGlobal(1);

                // Create a new byte. 
                byte b = 1;

                Console.WriteLine("Byte written to unmanaged memory: " + b);

                // Write the byte to unmanaged memory.
                Marshal.WriteByte(hGlobal, b);

                // Read byte from unmanaged memory. 
                byte c = Marshal.ReadByte(hGlobal);

                Console.WriteLine("Byte read from unmanaged memory: " + c);

                // Free the unmanaged memory.
                Marshal.FreeHGlobal(hGlobal);

                Console.Write("Unmanaged memory was disposed.");


            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }

            Console.Read();

        }
    }
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

  • SecurityCriticalAttribute 

    requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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