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



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

NNAAMMEE
       calloc -- a memory allocator

SSYYNNOOPPSSIISS
       #include <stdlib.h>

       void *calloc(size_t _n_e_l_e_m, size_t _e_l_s_i_z_e);

DDEESSCCRRIIPPTTIIOONN
       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 _c_a_l_l_o_c() function shall allocate unused space for an array of _n_e_l_e_m
       elements each of whose size in bytes is _e_l_s_i_z_e.  The space shall be
       initialized to all bits 0.

       The order and contiguity of storage allocated by successive calls to
       _c_a_l_l_o_c() 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.

RREETTUURRNN VVAALLUUEE
       Upon successful completion with both _n_e_l_e_m and _e_l_s_i_z_e non-zero,
       _c_a_l_l_o_c() shall return a pointer to the allocated space. If either _n_e_l_e_m
       or _e_l_s_i_z_e is 0, then either:

        *  A null pointer shall be returned and _e_r_r_n_o 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 _e_r_r_n_o to indicate the
       error.

EERRRROORRSS
       The _c_a_l_l_o_c() function shall fail if:

       EENNOOMMEEMM Insufficient memory is available.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       There is now no requirement for the implementation to support the
       inclusion of _<_m_a_l_l_o_c_._h_>.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _f_r_e_e(), _m_a_l_l_o_c(), _r_e_a_l_l_o_c()

       The Base Definitions volume of POSIX.1-2017, <<ssttddlliibb..hh>>

CCOOPPYYRRIIGGHHTT
       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(3)
