1CALLOC(3P)                 POSIX Programmer's Manual                CALLOC(3P)
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PROLOG

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

12       calloc — a memory allocator
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SYNOPSIS

15       #include <stdlib.h>
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17       void *calloc(size_t nelem, size_t elsize);
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DESCRIPTION

20       The functionality described on this reference page is aligned with  the
21       ISO C  standard.  Any  conflict between the requirements described here
22       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
23       defers to the ISO C standard.
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25       The calloc() function shall allocate unused space for an array of nelem
26       elements each of whose size in bytes is elsize.   The  space  shall  be
27       initialized to all bits 0.
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29       The  order  and  contiguity of storage allocated by successive calls to
30       calloc() is unspecified. The pointer returned if  the  allocation  suc‐
31       ceeds shall be suitably aligned so that it may be assigned to a pointer
32       to any type of object and then used to access  such  an  object  or  an
33       array  of  such  objects  in  the  space  allocated (until the space is
34       explicitly freed or reallocated). Each such allocation  shall  yield  a
35       pointer  to  an  object  disjoint  from  any  other object. The pointer
36       returned shall point to the start (lowest byte address)  of  the  allo‐
37       cated  space. If the space cannot be allocated, a null pointer shall be
38       returned. If the size of the space requested  is  0,  the  behavior  is
39       implementation-defined: either a null pointer shall be returned, or the
40       behavior shall be as if the size were some non-zero value, except  that
41       the  behavior is undefined if the returned pointer is used to access an
42       object.
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RETURN VALUE

45       Upon successful completion with both nelem and  elsize  non-zero,  cal‐
46       loc() shall return a pointer to the allocated space. If either nelem or
47       elsize is 0, then either:
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49        *  A null pointer shall be returned and errno may be set to an  imple‐
50           mentation-defined value, or
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52        *  A pointer to the allocated space shall be returned. The application
53           shall ensure that the pointer is not used to access an object.
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55       Otherwise, it shall return a null pointer and set errno to indicate the
56       error.
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ERRORS

59       The calloc() function shall fail if:
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61       ENOMEM Insufficient memory is available.
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63       The following sections are informative.
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EXAMPLES

66       None.
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APPLICATION USAGE

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

73       None.
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FUTURE DIRECTIONS

76       None.
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SEE ALSO

79       free(), malloc(), realloc()
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81       The Base Definitions volume of POSIX.1‐2017, <stdlib.h>
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84       Portions of this text are reprinted and reproduced in  electronic  form
85       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
86       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
87       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
88       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
89       event of any discrepancy between this version and the original IEEE and
90       The Open Group Standard, the original IEEE and The Open Group  Standard
91       is  the  referee document. The original Standard can be obtained online
92       at http://www.opengroup.org/unix/online.html .
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94       Any typographical or formatting errors that appear  in  this  page  are
95       most likely to have been introduced during the conversion of the source
96       files to man page format. To report such errors,  see  https://www.ker
97       nel.org/doc/man-pages/reporting_bugs.html .
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101IEEE/The Open Group                  2017                           CALLOC(3P)
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