Marshal.WriteInt32 Method

Definition

Namespace:

System.Runtime.InteropServices

Assembly:

System.Runtime.InteropServices.dll

Writes a 32-bit signed integer value to unmanaged memory. Writing to unaligned memory locations is supported.

Overloads

WriteInt32(Object, Int32, Int32)	Obsolete. Writes a 32-bit signed integer value to unmanaged memory at a specified offset.
WriteInt32(IntPtr, Int32)	Writes a 32-bit signed integer value to unmanaged memory.
WriteInt32(IntPtr, Int32, Int32)	Writes a 32-bit signed integer value into unmanaged memory at a specified offset.

WriteInt32(Object, Int32, Int32)

Source:

Marshal.CoreCLR.cs

Caution

WriteInt32(Object, Int32, Int32) may be unavailable in future releases.

Writes a 32-bit signed integer value to unmanaged memory at a specified offset.

public:
 static void WriteInt32(System::Object ^ ptr, int ofs, int val);

[System.Obsolete("WriteInt32(Object, Int32, Int32) may be unavailable in future releases.")]
public static void WriteInt32 (object ptr, int ofs, int val);

[<System.Obsolete("WriteInt32(Object, Int32, Int32) may be unavailable in future releases.")>]
static member WriteInt32 : obj * int * int -> unit

Public Shared Sub WriteInt32 (ptr As Object, ofs As Integer, val As Integer)

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

Int32

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

WriteInt32 enables direct interaction with an unmanaged 32-bit signed array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before setting its element values.

Writing to unaligned memory locations is supported.

See also

• Copy(Int32[], Int32, IntPtr, Int32)

WriteInt32(IntPtr, Int32)

Source:

Marshal.cs

Writes a 32-bit signed integer value to unmanaged memory.

public:
 static void WriteInt32(IntPtr ptr, int val);

public static void WriteInt32 (IntPtr ptr, int val);

static member WriteInt32 : nativeint * int -> unit

Public Shared Sub WriteInt32 (ptr As IntPtr, val As Integer)

Parameters

ptr

IntPtr

nativeint

The address in unmanaged memory to write to.

val

Int32

The value to write.

Exceptions

AccessViolationException

ptr is not a recognized format.

-or-

ptr is null.

-or-

ptr is invalid.

Examples

The following example demonstrates how to read and write to an unmanaged array using the ReadInt32 and WriteInt32 methods.

static void ReadWriteInt32()
{
    // Allocate unmanaged memory. 
    int elementSize = 4;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteInt32(unmanagedArray, i * elementSize, ((Int32)(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.ReadInt32(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

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

Sub ReadWriteInt32()
    ' Allocate unmanaged memory. 
    Dim elementSize As Integer = 4
    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.WriteInt32(unmanagedArray, i * elementSize, CType(i + 1, Int32))
    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.ReadInt32(unmanagedArray, i * elementSize))
    Next i

    Marshal.FreeHGlobal(unmanagedArray)

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

Remarks

WriteInt32 enables direct interaction with an unmanaged 32-bit signed array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before setting its element values.

Writing to unaligned memory locations is supported.

See also

• Copy(Int32[], Int32, IntPtr, Int32)

WriteInt32(IntPtr, Int32, Int32)

Source:

Marshal.cs

Writes a 32-bit signed integer value into unmanaged memory at a specified offset.

public:
 static void WriteInt32(IntPtr ptr, int ofs, int val);

public static void WriteInt32 (IntPtr ptr, int ofs, int val);

static member WriteInt32 : nativeint * int * int -> unit

Public Shared Sub WriteInt32 (ptr As IntPtr, ofs As Integer, val As Integer)

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

Int32

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 ReadInt32 and WriteInt32 methods.

static void ReadWriteInt32()
{
    // Allocate unmanaged memory. 
    int elementSize = 4;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteInt32(unmanagedArray, i * elementSize, ((Int32)(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.ReadInt32(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

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

Sub ReadWriteInt32()
    ' Allocate unmanaged memory. 
    Dim elementSize As Integer = 4
    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.WriteInt32(unmanagedArray, i * elementSize, CType(i + 1, Int32))
    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.ReadInt32(unmanagedArray, i * elementSize))
    Next i

    Marshal.FreeHGlobal(unmanagedArray)

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

Remarks

WriteInt32 enables direct interaction with an unmanaged 32-bit signed array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before setting its element values.

Writing to unaligned memory locations is supported.

See also

• Copy(Int32[], Int32, IntPtr, Int32)
• WriteByte(IntPtr, Int32, Byte)