Marshal.WriteInt64 Method (Object, 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)

static member WriteInt64 : 
        ptr:Object *
        ofs:int *
        val:int64 -> unit


Type: System.Object

The base address in unmanaged memory of the target object.

Type: System.Int32

An additional byte offset, which is added to the ptr parameter before writing.

Type: System.Int64

The value to write.

Exception Condition

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


ptr is an ArrayWithOffset object. This method does not accept ArrayWithOffset parameters.

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.


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
Windows Phone
Available since 8.1
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