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Marshal.ReadInt16 Method (IntPtr, Int32)

Reads a 16-bit signed integer from unmanaged memory.

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

public static short ReadInt16 (
	IntPtr ptr,
	int ofs
)
public static short ReadInt16 (
	IntPtr ptr, 
	int ofs
)
public static function ReadInt16 (
	ptr : IntPtr, 
	ofs : int
) : short
Not applicable.

Parameters

ptr

The base address in unmanaged memory from which to read.

ofs

An additional byte offset, added to the ptr parameter before reading.

Return Value

The 16-bit signed integer read from ptr.

Exception typeCondition

AccessViolationException

Base address (ptr) plus offset byte (ofs) produces a a null reference (Nothing in Visual Basic) or invalid address.

ReadInt16 enables direct interaction with an unmanaged 16-bit signed array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before reading 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 demonstrates how to read and write to an unmanaged array using the ReadInt16 and WriteInt16 methods.

static void ReadWriteInt16()
{
    // Allocate unmanaged memory. 
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10);

    // One way to set the 10 elements of the C-style unmanagedArray
    Int16[] newArray = new Int16[10];


    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteInt16(unmanagedArray, i * Marshal.SizeOf(typeof(Int16)), ((Int16)(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.ReadInt16(unmanagedArray, i * Marshal.SizeOf(typeof(Int16))));
    }

    Marshal.FreeHGlobal(unmanagedArray);

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

}

The following code example demonstrates how to use the ReadInt16 method to read the value of an unmanaged short variable.


using namespace System;
using namespace System::Runtime::InteropServices;

void main()
{
    // Create an unmanaged short pointer.
    short * myShort;
    short tmp = 42;
    // Initialize it to another value.
    myShort = &tmp;

    // Read value as a managed Int16.
    Int16 ^ myManagedVal = Marshal::ReadInt16((IntPtr) myShort, 0);

    // Display the value to the console.
    Console::WriteLine(myManagedVal);
}

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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