Runs consistency checks on the heap.

int _heapchk( void );

_heapchk returns one of the following integer manifest constants defined in Malloc.h.


Initial header information is bad or cannot be found.


Bad node has been found or heap is damaged.


Pointer into heap is not valid.


Heap has not been initialized.


Heap appears to be consistent.

In addition, if an error occurs, _heapchk sets errno to ENOSYS.

The _heapchk function helps debug heap-related problems by checking for minimal consistency of the heap. If the operating system does not support _heapchk(for example, Windows 98), the function returns _HEAPOK and sets errno to ENOSYS.


Required header

Optional header




For more compatibility information, see Compatibility in the Introduction.

// crt_heapchk.c
// This program checks the heap for
// consistency and prints an appropriate message.
#include <malloc.h>
#include <stdio.h>

int main( void )
   int  heapstatus;
   char *buffer;

   // Allocate and deallocate some memory
   if( (buffer = (char *)malloc( 100 )) != NULL )
      free( buffer );

   // Check heap status
   heapstatus = _heapchk();
   switch( heapstatus )
   case _HEAPOK:
      printf(" OK - heap is fine\n" );
   case _HEAPEMPTY:
      printf(" OK - heap is empty\n" );
      printf( "ERROR - bad start of heap\n" );
      printf( "ERROR - bad node in heap\n" );
 OK - heap is fine

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.