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MSDN Library

Marshal.ReAllocHGlobal Method

Resizes a block of memory previously allocated with AllocHGlobal.

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

public static IntPtr ReAllocHGlobal(
	IntPtr pv,
	IntPtr cb


Type: System.IntPtr

A pointer to memory allocated with AllocHGlobal.

Type: System.IntPtr

The new size of the allocated block. This is not a pointer; it is the byte count you are requesting, cast to type IntPtr. If you pass a pointer, it is treated as a size.

Return Value

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


There is insufficient memory to satisfy the request.

ReAllocHGlobal is one of two memory reallocation API methods in the Marshal class. (Marshal.ReAllocCoTaskMem is the other.)

This method exposes the Win32 GlobalReAlloc function from Kernel32.dll. The returned pointer can differ from the original. If it is different, the contents of the original memory block have been copied to the new block, and the original memory block has been freed.

.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

.NET for Windows Phone apps

Supported in: Windows Phone 8.1

Portable Class Library

Supported in: Portable Class Library

  • SecurityCriticalAttribute 

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

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