Syntax

#include <malloc.h>
int _heapchk(void);

• heapchk checks the default storage heap for minimal consistency by checking all allocated and freed objects on the heap.

  A heap-specific version of this function, _uheapchk, is also available.

  Note: Using the _heapchk, _heapset, and _heap_walk functions (and their heap-specific equivalents) may add overhead to each object allocated from the heap.

• heapchk returns one of the following values, defined in <malloc.h>:

• HEAPBADBEGIN
  The heap specified is not valid. (Only occurs if you changed the default heap and then later closed or destroyed it.)
  _HEAPBADNODE
  A memory node is corrupted, or the heap is damaged.
  _HEAPEMPTY
  The heap has not been initialized.
  _HEAPOK
  The heap appears to be consistent.

This example performs some memory allocations, then calls _heapchk to check the heap.

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

int main(void)
{
   char *ptr;
   int  rc;

   if (NULL == (ptr = malloc(10))) {
      puts("Could not allocate memory block.");
      exit(EXIT_FAILURE);
   }
   *(ptr - 1) = 'x';      /* overwrites storage that was not allocated */

   if (_HEAPOK != (rc = _heapchk())) {
      switch(rc) {
         case _HEAPEMPTY:
            puts("The heap has not been initialized.");
            break;
         case _HEAPBADNODE:
            puts("A memory node is corrupted or the heap is damaged.");
            break;
         case _HEAPBADBEGIN:
            puts("The heap specified is not valid.");
            break;
      }
      exit(rc);
   }
   free(ptr);
   return 0;

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

      A memory node is corrupted or the heap is damaged.
   ****************************************************************************/
}

• Managing Memory" in the VisualAge C++ Programming Guide
  
• uheapchk
  
• heapmin
  
• heapset
  
• heap_walk

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