calloc

CALLOC(3POSIX)              POSIX Programmer's Manual             CALLOC(3POSIX)

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)