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Marshal.SizeOf Method (Object)

Returns the unmanaged size of an object in bytes.

Namespace:  System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)

[ComVisibleAttribute(true)]
public static int SizeOf(
	Object structure
)

Parameters

structure
Type: System.Object

The object whose size is to be returned.

Return Value

Type: System.Int32
The size of the specified object in unmanaged code.

ExceptionCondition
ArgumentNullException

The structure parameter is null.

This method accepts an instance of a structure, which can be a reference type or a boxed value type. The layout must be sequential or explicit.

The size returned is the size of the unmanaged object. The unmanaged and managed sizes of an object can differ. For character types, the size is affected by the CharSet value applied to that class.

You can use the SizeOf method to determine how much unmanaged memory to allocate using the AllocHGlobal and AllocCoTaskMem methods.

The following example creates a managed structure, transfers it to unmanaged memory, and then transfers it back to managed memory. This example uses the SizeOf method to determine how much unmanaged memory to allocate.

using System;
using System.Runtime.InteropServices;

public struct Point
{
    public int x;
    public int y;
}

class Example
{

    static void Main()
    {

        // Create a point struct.
        Point p;
        p.x = 1;
        p.y = 1;

        Console.WriteLine("The value of first point is " + p.x + " and " + p.y + ".");

        // Initialize unmanged memory to hold the struct.
        IntPtr pnt = Marshal.AllocHGlobal(Marshal.SizeOf(p));

        try
        {

            // Copy the struct to unmanaged memory.
            Marshal.StructureToPtr(p, pnt, false);

            // Create another point.
            Point anotherP;

            // Set this Point to the value of the  
            // Point in unmanaged memory. 
            anotherP = (Point)Marshal.PtrToStructure(pnt, typeof(Point));

            Console.WriteLine("The value of new point is " + anotherP.x + " and " + anotherP.y + ".");

        }
        finally
        {
            // Free the unmanaged memory.
            Marshal.FreeHGlobal(pnt);
        }



    }

}

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

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

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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