Export (0) Print
Expand All

Marshal.WriteInt64 Method (IntPtr, Int32, Int64)

Writes a 64-bit signed integer value to unmanaged memory at a specified offset.

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

public static void WriteInt64(
	IntPtr ptr,
	int ofs,
	long val
)

Parameters

ptr
Type: System.IntPtr
The base address in unmanaged memory to write.
ofs
Type: System.Int32
An additional byte offset, which is added to the ptr parameter before writing.
val
Type: System.Int64
The value to write.

ExceptionCondition
AccessViolationException

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

WriteInt64 enables direct interaction with an unmanaged 64-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.

The following example demonstrates how to read and write to an unmanaged array using the ReadInt64 and WriteInt64 methods.


static void ReadWriteInt64()
{
    // Allocate unmanaged memory. 
    int elementSize = 8;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteInt64(unmanagedArray, i * elementSize, ((Int64)(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.ReadInt64(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

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


.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

  • SecurityCriticalAttribute 

    requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Community Additions

ADD
Show:
© 2014 Microsoft