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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
)
public static void WriteByte (
	IntPtr ptr, 
	byte val
)
public static function WriteByte (
	ptr : IntPtr, 
	val : byte
)
Not applicable.

Parameters

ptr

The address in unmanaged to write.

val

The value to write.

Exception typeCondition

AccessViolationException

ptr is not a recognized format.

-or-

ptr is a null reference (Nothing in Visual Basic).

-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.

NoteNote:

This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

The following code 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();

        }
    }
}

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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