`_heapchk`

Article
12/02/2022

Runs consistency checks on the heap.

Syntax

int _heapchk( void );

Return value

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

Return value	Condition
`_HEAPBADBEGIN`	Initial header information is bad or can't be found.
`_HEAPBADNODE`	Bad node has been found or heap is damaged.
`_HEAPBADPTR`	Pointer into heap isn't valid.
`_HEAPEMPTY`	Heap hasn't been initialized.
`_HEAPOK`	Heap appears to be consistent.

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

Remarks

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

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Routine	Required header	Optional header
`_heapchk`	<malloc.h>	<errno.h>

For more compatibility information, see Compatibility.

Example

// 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" );
      break;
   case _HEAPEMPTY:
      printf(" OK - heap is empty\n" );
      break;
   case _HEAPBADBEGIN:
      printf( "ERROR - bad start of heap\n" );
      break;
   case _HEAPBADNODE:
      printf( "ERROR - bad node in heap\n" );
      break;
   }
}

OK - heap is fine