Marshal.WriteByte Method

Definition

Namespace:

System.Runtime.InteropServices

Assemblies:

netstandard.dll, System.Runtime.InteropServices.dll

Writes a single byte value to unmanaged memory.

Overloads

WriteByte(Object, Int32, Byte)	Obsolete. Writes a single byte value to unmanaged memory at a specified offset.
WriteByte(IntPtr, Byte)	Writes a single byte value to unmanaged memory.
WriteByte(IntPtr, Int32, Byte)	Writes a single byte value to unmanaged memory at a specified offset.

WriteByte(Object, Int32, Byte)

Source:

Marshal.CoreCLR.cs

Caution

WriteByte(Object, Int32, Byte) may be unavailable in future releases.

Writes a single byte value to unmanaged memory at a specified offset.

C#

[System.Obsolete("WriteByte(Object, Int32, Byte) may be unavailable in future releases.")]
public static void WriteByte(object ptr, int ofs, byte val);

Parameters

ptr

Object

The base address in unmanaged memory of the target object.

ofs

Int32

An additional byte offset, which is added to the ptr parameter before writing.

val

Byte

The value to write.

Attributes

ObsoleteAttribute

Exceptions

AccessViolationException

Base address (ptr) plus offset byte (ofs) produces a null or invalid address.

ArgumentException

ptr is an ArrayWithOffset object. This method does not accept ArrayWithOffset parameters.

Remarks

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.

See also

• Copy(Int32[], Int32, IntPtr, Int32)

WriteByte(IntPtr, Byte)

Source:

Marshal.cs

Writes a single byte value to unmanaged memory.

C#

public static void WriteByte(IntPtr ptr, byte val);

Parameters

ptr

IntPtr

The address in unmanaged memory to write to.

val

Byte

The value to write.

Exceptions

AccessViolationException

ptr is not a recognized format.

-or-

ptr is null.

-or-

ptr is invalid.

Examples

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.

C#

using System;
using System.Runtime.InteropServices;

 class Example
 {
     static void Main(string[] args)
     {
          // 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.WriteLine("Unmanaged memory was disposed.");
     }
}

Remarks

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.

See also

• Copy(Int32[], Int32, IntPtr, Int32)

WriteByte(IntPtr, Int32, Byte)

Source:

Marshal.cs

Writes a single byte value to unmanaged memory at a specified offset.

C#

public static void WriteByte(IntPtr ptr, int ofs, byte val);

Parameters

ptr

IntPtr

The base address in unmanaged memory to write to.

ofs

Int32

An additional byte offset, which is added to the ptr parameter before writing.

val

Byte

The value to write.

Exceptions

AccessViolationException

Base address (ptr) plus offset byte (ofs) produces a null or invalid address.

Examples

The following example demonstrates how to read and write to an unmanaged array using the ReadByte and WriteByte methods.

C#

static void ReadWriteByte()
{
    // Allocate unmanaged memory. 
    int elementSize = 1;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteByte(unmanagedArray, i * elementSize, ((Byte)(i + 1)));
    }
    Console.WriteLine("Unmanaged memory written.");

    Console.WriteLine("Reading unmanaged memory:");
    // Print the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Console.WriteLine(Marshal.ReadByte(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

    Console.WriteLine("Done. Press Enter to continue.");
    Console.ReadLine();
}

Remarks

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.

See also

• Copy(Int32[], Int32, IntPtr, Int32)