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 .

IEEE/The Open Group                                   2003                                            REALLOC(P)