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)

[SecurityCriticalAttribute]
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.

Exception Condition
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();
}

SecurityCriticalAttribute

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

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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