Marshal.WriteByte Method

Definition

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)

Caution

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

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

public:
 static void WriteByte(System::Object ^ ptr, int ofs, System::Byte val);
[System.Obsolete("WriteByte(Object, Int32, Byte) may be unavailable in future releases.")]
[System.Security.SecurityCritical]
public static void WriteByte (object ptr, int ofs, byte val);
[System.Obsolete("WriteByte(Object, Int32, Byte) may be unavailable in future releases.")]
public static void WriteByte (object ptr, int ofs, byte val);
public static void WriteByte (object ptr, int ofs, byte val);
[System.Security.SecurityCritical]
public static void WriteByte (object ptr, int ofs, byte val);
[<System.Obsolete("WriteByte(Object, Int32, Byte) may be unavailable in future releases.")>]
[<System.Security.SecurityCritical>]
static member WriteByte : obj * int * byte -> unit
[<System.Obsolete("WriteByte(Object, Int32, Byte) may be unavailable in future releases.")>]
static member WriteByte : obj * int * byte -> unit
static member WriteByte : obj * int * byte -> unit
[<System.Security.SecurityCritical>]
static member WriteByte : obj * int * byte -> unit
Public Shared Sub WriteByte (ptr As Object, ofs As Integer, val As Byte)

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

Exceptions

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

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

Applies to

WriteByte(IntPtr, Byte)

Writes a single byte value to unmanaged memory.

public:
 static void WriteByte(IntPtr ptr, System::Byte val);
[System.Security.SecurityCritical]
public static void WriteByte (IntPtr ptr, byte val);
public static void WriteByte (IntPtr ptr, byte val);
[<System.Security.SecurityCritical>]
static member WriteByte : nativeint * byte -> unit
static member WriteByte : nativeint * byte -> unit
Public Shared Sub WriteByte (ptr As IntPtr, val As Byte)

Parameters

ptr
IntPtr

nativeint

The address in unmanaged memory to write to.

val
Byte

The value to write.

Attributes

Exceptions

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.

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.");
     }
}
Imports System.Runtime.InteropServices

Module Example
    Sub Main()
         ' Allocate 1 byte of unmanaged memory.
         Dim hGlobal As IntPtr = Marshal.AllocHGlobal(1)
         
         ' Create a new byte.
         Dim b As Byte = 1
         
         Console.WriteLine("Byte written to unmanaged memory: {0}", b)
         
         ' Write the byte to unmanaged memory.
         Marshal.WriteByte(hGlobal, b)
         
         ' Read byte from unmanaged memory.
         Dim c As Byte = Marshal.ReadByte(hGlobal)
         Console.WriteLine("Byte read from unmanaged memory: {0}", c)
         
         ' Free the unmanaged memory.
         Marshal.FreeHGlobal(hGlobal)
         Console.WriteLine("Unmanaged memory was disposed.")
    End Sub
End Module

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

Applies to

WriteByte(IntPtr, Int32, Byte)

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

public:
 static void WriteByte(IntPtr ptr, int ofs, System::Byte val);
[System.Security.SecurityCritical]
public static void WriteByte (IntPtr ptr, int ofs, byte val);
public static void WriteByte (IntPtr ptr, int ofs, byte val);
[<System.Security.SecurityCritical>]
static member WriteByte : nativeint * int * byte -> unit
static member WriteByte : nativeint * int * byte -> unit
Public Shared Sub WriteByte (ptr As IntPtr, ofs As Integer, val As Byte)

Parameters

ptr
IntPtr

nativeint

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.

Attributes

Exceptions

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.

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();
}
Sub ReadWriteByte()
    ' Allocate unmanaged memory. 
    Dim elementSize As Integer = 1
    Dim unmanagedArray As IntPtr = Marshal.AllocHGlobal(10 * elementSize)

    ' Set the 10 elements of the C-style unmanagedArray
    For i As Integer = 0 To 9
        Marshal.WriteByte(unmanagedArray, i * elementSize, CType(i + 1, Byte))
    Next i
    Console.WriteLine("Unmanaged memory written.")

    Console.WriteLine("Reading unmanaged memory:")
    ' Print the 10 elements of the C-style unmanagedArray
    For i As Integer = 0 To 9
        Console.WriteLine(Marshal.ReadByte(unmanagedArray, i * elementSize))
    Next i

    Marshal.FreeHGlobal(unmanagedArray)

    Console.WriteLine("Done. Press Enter to continue.")
    Console.ReadLine()
End Sub

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

Applies to