Marshal.WriteByte Method (IntPtr, Byte)

Writes a single byte value to unmanaged memory.

Namespace:  System.Runtime.InteropServices
Assemblies:   System.Runtime.InteropServices (in System.Runtime.InteropServices.dll)
  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: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

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

Portable Class Library

Supported in: Portable Class Library

  • SecurityCriticalAttribute 

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

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