9.2 Memory Interface
Keywords: api

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9.2 Memory Interface

The following function sets, modeled after the ANSI C standard, are available for allocating and releasing memory from the Python heap:

void* `PyMem_Malloc` (size_t n)
  Allocates n bytes and returns a pointer of type `void*` to the allocated memory, or `NULL` if the request fails. Requesting zero bytes returns a non-`NULL` pointer.

void* `PyMem_Realloc` (void *p, size_t n)
  Resizes the memory block pointed to by p to n bytes. The contents will be unchanged to the minimum of the old and the new sizes. If p is `NULL`, the call is equivalent to `PyMem_Malloc(n)`; if n is equal to zero, the memory block is resized but is not freed, and the returned pointer is non-`NULL`. Unless p is `NULL`, it must have been returned by a previous call to `PyMem_Malloc()` or `PyMem_Realloc()`.

void `PyMem_Free` (void *p)
  Frees the memory block pointed to by p, which must have been returned by a previous call to `PyMem_Malloc()` or `PyMem_Realloc()`. Otherwise, or if `PyMem_Free(p)` has been called before, undefined behaviour occurs. If p is `NULL`, no operation is performed.

The following type-oriented macros are provided for convenience. Note that TYPE refers to any C type.

TYPE* `PyMem_New` (TYPE, size_t n)
  Same as `PyMem_Malloc()`, but allocates `(n * sizeof(TYPE))` bytes of memory. Returns a pointer cast to `TYPE*`.

TYPE* `PyMem_Resize` (void *p, TYPE, size_t n)
  Same as `PyMem_Realloc()`, but the memory block is resized to `(n * sizeof(TYPE))` bytes. Returns a pointer cast to `TYPE*`.

void `PyMem_Del` (void *p)
  Same as `PyMem_Free()`.

In addition, the following macro sets are provided for calling the Python memory allocator directly, without involving the C API functions listed above. However, note that their use does not preserve binary compatibility accross Python versions and is therefore deprecated in extension modules.

`PyMem_MALLOC()`, `PyMem_REALLOC()`, `PyMem_FREE()`.

`PyMem_NEW()`, `PyMem_RESIZE()`, `PyMem_DEL()`.