_mheap - Query Memory Heap for Allocated Object

Syntax

#include <umalloc.h>
Heap_t _mheap(void *ptr);

mheap determines from which heap the object specified by ptr was allocated. The ptr must be a valid pointer that was returned from a run-time allocation function (_ucalloc, malloc, realloc, and so on). If the pointer is not valid, the results of _mheap are undefined.
For more information about creating and using heaps, see the chapter on Managing Memory in the VisualAge C++ Programming Guide.

mheap returns the handle of the heap from which the object was allocated. If the object was allocated from the run-time heap, _mheap returns _RUNTIME_HEAP. If the object passed to _mheap is NULL, _mheap returns NULL. If the object is not valid, _mheap either returns NULL (depending on how closely the storage pointed to resembles a valid object), or an exception occurs.

This example allocates a block of memory from the heap, then uses _mheap to determine which heap the block came from.

#include <stdlib.h>
#include <stdio.h>
#include <umalloc.h>

int main(void)
{
   char  *ptr;

   if (NULL == (ptr = malloc(10))) {
      puts("Could not allocate memory block.");
      exit(EXIT_FAILURE);
   }
   printf("Handle of heap used is 0x%x\n", _mheap(ptr));
   return 0;

   /****************************************************************************
      The output should be similar to :

      Handle of heap used is 0x70000
   ****************************************************************************/
}

Managing Memory" in the VisualAge C++ Programming Guide
msize
ucreate
ustats

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