CALLOC(3P) POSIX Programmer's Manual CALLOC(3P)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.
NAMEcalloc — a memory allocator
void *calloc(size_t nelem, size_t elsize);
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.1‐2008
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 suc‐
ceeds 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 allo‐
cated 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: the value returned shall be either a null
pointer or a unique pointer.
Upon successful completion with both nelem and elsize non-zero, cal‐
loc() shall return a pointer to the allocated space. If either nelem or
elsize is 0, then either a null pointer or a unique pointer value that
can be successfully passed to free() shall be returned. Otherwise, it
shall return a null pointer and set errno to indicate the error.
The calloc() function shall fail if:
ENOMEM Insufficient memory is available.
The following sections are informative.
There is now no requirement for the implementation to support the
inclusion of <malloc.h>.
SEE ALSOfree(), malloc(), realloc()
The Base Definitions volume of POSIX.1‐2008, <stdlib.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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.ker‐
IEEE/The Open Group 2013 CALLOC(3P)