NAME

       realloc - memory reallocator

SYNOPSIS

       #include <stdlib.h>

       void *realloc(void *ptr, size_t size);

DESCRIPTION

       The realloc() function shall change the size of the memory object pointed to by ptr to the
       size specified by size. The contents of the object shall remain unchanged up to the lesser
       of  the  new and old sizes. If the new size of the memory object would require movement of
       the object, the space for the previous instantiation of the object is freed.  If  the  new
       size is larger, the contents of the newly allocated portion of the object are unspecified.
       If size is 0 and ptr is not a null pointer, the object pointed to is freed. If  the  space
       cannot be allocated, the object shall remain unchanged.

       If  ptr  is  a  null  pointer, realloc() shall be equivalent to malloc() for the specified
       size.

       If ptr does not match a pointer returned earlier by calloc(), malloc(), or realloc() or if
       the  space  has previously been deallocated by a call to free() or realloc(), the behavior
       is undefined.

       The order and contiguity  of  storage  allocated  by  successive  calls  to  realloc()  is
       unspecified.  The pointer returned if the allocation succeeds shall be suitably aligned so
       that it may be assigned to a pointer to any type of object and then used to access such an
       object  in  the space allocated (until the space is explicitly freed or reallocated). Each
       such allocation shall yield a pointer to an object disjoint from  any  other  object.  The
       pointer returned shall point to the start (lowest byte address) of the allocated space. If
       the space cannot be allocated, a null pointer shall be returned.

RETURN VALUE

       Upon successful completion with a size not equal to 0, realloc() shall return a pointer to
       the  (possibly  moved)  allocated  space.  If size is 0, either a null pointer or a unique
       pointer that can be successfully passed to free() shall be  returned.   If  there  is  not
       enough  available  memory,  realloc()  shall  return  a  null  pointer    and set errno to
       [ENOMEM].

ERRORS

       The realloc() function shall fail if:

       ENOMEM Insufficient memory is available.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       calloc() , free() , malloc()  ,  the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <stdlib.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .