_msize

Returns the size of a memory block allocated in the heap.

size_t _msize( void *memblock );

For additional compatibility information, see Compatibility in the Introduction.

Libraries

Return Value

_msize returns the size (in bytes) as an unsigned integer.

Parameter

memblock

Pointer to memory block

Remarks

The _msize function returns the size, in bytes, of the memory block allocated by a call to calloc, malloc, or realloc.

When the application is linked with a debug version of the C run-time libraries, _msize resolves to _msize_dbg. For more information about how the heap is managed during the debugging process, see Using C Run-Time Library Debugging Support.

Example

/* REALLOC.C: This program allocates a block of memory for
 * buffer and then uses _msize to display the size of that
 * block. Next, it uses realloc to expand the amount of
 * memory used by buffer and then calls _msize again to
 * display the new amount of memory allocated to buffer.
 */

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

void main( void )
{
   long *buffer;
   size_t size;

   if( (buffer = (long *)malloc( 1000 * sizeof( long ) )) == NULL )
      exit( 1 );

   size = _msize( buffer );
   printf( "Size of block after malloc of 1000 longs: %u\n", size );

   /* Reallocate and show new size: */
   if( (buffer = realloc( buffer, size + (1000 * sizeof( long )) )) 
        ==  NULL )
      exit( 1 );
   size = _msize( buffer );
   printf( "Size of block after realloc of 1000 more longs: %u\n", 
            size );

   free( buffer );
   exit( 0 );
}

Output

Size of block after malloc of 1000 longs: 4000
Size of block after realloc of 1000 more longs: 8000

Memory Allocation Routines

See Also   calloc, _expand, malloc, realloc