PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       calloc — a memory allocator

SYNOPSIS

       #include <stdlib.h>

       void *calloc(size_t nelem, size_t elsize);

DESCRIPTION

       The  functionality  described  on  this  reference  page is aligned with the ISO C standard. Any conflict
       between the requirements described  here  and  the  ISO C  standard  is  unintentional.  This  volume  of
       POSIX.1‐2017 defers to the ISO C standard.

       The  calloc()  function  shall allocate unused space for an array of nelem elements each of whose size in
       bytes is elsize.  The space shall be initialized to all bits 0.

       The order and contiguity of storage allocated by successive calls to calloc() 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 or an array of such objects 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.  If the size of the space requested is 0, the behavior is implementation-defined: either a null
       pointer shall be returned, or the behavior shall be as if the size were some non-zero value, except  that
       the behavior is undefined if the returned pointer is used to access an object.

RETURN VALUE

       Upon  successful  completion  with both nelem and elsize non-zero, calloc() shall return a pointer to the
       allocated space. If either nelem or elsize is 0, then either:

        *  A null pointer shall be returned and errno may be set to an implementation-defined value, or

        *  A pointer to the allocated space shall be returned. The application shall ensure that the pointer  is
           not used to access an object.

       Otherwise, it shall return a null pointer and set errno to indicate the error.

ERRORS

       The calloc() function shall fail if:

       ENOMEM Insufficient memory is available.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       There is now no requirement for the implementation to support the inclusion of <malloc.h>.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       free(), malloc(), realloc()

       The Base Definitions volume of POSIX.1‐2017, <stdlib.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                        CALLOC(3POSIX)