Marshal.AllocHGlobal Method (IntPtr) (System.Runtime.InteropServices)

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.NET Framework Class Library

Marshal.AllocHGlobal Method (IntPtr)

Allocates memory from the unmanaged memory of the process by using the pointer to the specified number of bytes.

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

Syntax

Visual Basic

Public Shared Function AllocHGlobal ( _
	cb As IntPtr _
) As IntPtr

public static IntPtr AllocHGlobal(
	IntPtr cb
)

Visual C++

public:
static IntPtr AllocHGlobal(
	IntPtr cb
)

static member AllocHGlobal : 
        cb:IntPtr -> IntPtr

Parameters

cb: Type: System.IntPtr
The required number of bytes in memory.

Return Value

Type: System.IntPtr
A pointer to the newly allocated memory. This memory must be released using the Marshal.FreeHGlobal method.

Exceptions

Exception	Condition
OutOfMemoryException	There is insufficient memory to satisfy the request.

Remarks

AllocHGlobal is one of two memory allocation methods in the Marshal class. (Marshal.AllocCoTaskMem is the other.) This method exposes the Win32 LocalAlloc function from Kernel32.dll.

When AllocHGlobal calls LocalAlloc, it passes a LMEM_FIXED flag, which causes the allocated memory to be locked in place. Also, the allocated memory is not zero-filled.

Version Information

.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

.NET Framework Security

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

Platforms

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.

Reference

Marshal Class

AllocHGlobal Overload

System.Runtime.InteropServices Namespace

AllocCoTaskMem

FreeHGlobal

Community Content

romkyns

Takes a byte count directly, not a pointer to one.

The introductory sentence is completely misleading:

Allocates memory from the unmanaged memory of the process by using the pointer to the specified number of bytes.

whereas in reality it just takes the number of bytes directly.