.\" Copyright 1993, David Metcalfe <david@prism.demon.co.uk>
.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH memory.h 3head 2026-08-10 "Linux man-pages 6.19"
.SH NAME
memory.h \- memory operations
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.B #include <memory.h>
.fi
.SH DESCRIPTION
.SS Write
.TP
.BR bzero (3)
.TQ
.BR explicit_bzero (3)
.TQ
.BR memset (3)
.TQ
.BR memset_explicit (3)
.SS Copy
.TP
.BR memmove (3)
.TQ
.BR memcpy (3)
.TQ
.BR mempcpy (3)
.TQ
.BR memccpy (3)
.TQ
.BR strncpy (3)
.TQ
.BR stpncpy (3)
.SS Catenate
.TP
.BR strncat (3)
.SS Duplicate
.TP
.BR strndup (3)
.TQ
.BR strndupa (3)
.SS Compare
.TP
.BR memeq (3)
.TQ
.BR memcmp (3)
.TQ
.BR strncmp (3)
.TQ
.BR strncasecmp (3)
.SS Search
.TP
.BR memchr (3)
.TQ
.BR memrchr (3)
.TQ
.BR memmem (3)
.SH VERSIONS
In some systems (Illumos),
.I <memory.h>
contains only a few of these functions,
and thus
.I <string.h>
is needed.
.SH STANDARDS
BSD.
.P
These functions are also provided in
.IR <string.h> ,
as specified by ISO C.
This is a historic mistake maintained for compatibility reasons;
these functions aren't string APIs.
.SH HISTORY
SVr1, 4.3BSD.
.P
System V (1983)
introduced an initial set of mem* functions
in a
.I <memory.h>
header file.
4.3BSD (1986)
adopted them.
.P
SVID Issue 1 (1985) standardized this header file,
but stated that the functions would be moved to
.IR <string.h> .
.P
XPG Issue 3 (1989) listed
.I <memory.h>
as WITHDRAWN,
and stated that the functions had been moved to
.IR <string.h> .
.P
C89 didn't standardize this header file
and instead specified all these functions in
.IR <string.h> .
.P
This merge of header files
has historically confused programmers
about the real purpose of these functions.
.P
Most C libraries, including the BSDs, glibc, musl, Bionic, and Illumos
continue to provide
.I <memory.h>.
.P
gnulib doesn't provide it, though,
and instead uses
.IR <string.h> .
.SH SEE ALSO
.BR string (3),
.BR string_copying (7)