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Marshal.AllocHGlobal Method (Int32)

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

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

public static IntPtr AllocHGlobal(
	int cb
)

Parameters

cb
Type: System.Int32

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.

ExceptionCondition
OutOfMemoryException

There is insufficient memory to satisfy the request.

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.

The following example demonstrates calling the AllocHGlobal method. This code example is part of a larger example provided for the Marshal class.

// Demonstrate how to call GlobalAlloc and  
// GlobalFree using the Marshal class.
IntPtr hglobal = Marshal.AllocHGlobal(100);
Marshal.FreeHGlobal(hglobal);

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

  • SecurityCriticalAttribute 

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

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