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 .