NetBSD/lib/libc/string/strcpy.3

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.\" Copyright (c) 1990, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
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.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" from: @(#)strcpy.3 8.1 (Berkeley) 6/4/93
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.\" $NetBSD: strcpy.3,v 1.14 2003/05/06 10:10:41 wiz Exp $
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.\"
.Dd May 6, 2002
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.Dt STRCPY 3
.Os
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.Sh NAME
.Nm strcpy ,
.Nm strncpy
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.Nd copy strings
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.Sh LIBRARY
.Lb libc
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.Sh SYNOPSIS
.In string.h
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.Ft char *
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.Fn strcpy "char * restrict dst" "const char * restrict src"
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.Ft char *
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.Fn strncpy "char * restrict dst" "const char * restrict src" "size_t len"
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.Sh DESCRIPTION
The
.Fn strcpy
and
.Fn strncpy
functions
copy the string
.Fa src
to
.Fa dst
(including the terminating
.Ql \e0
character).
.Pp
The
.Fn strncpy
function copies not more than
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.Fa len
characters into
.Fa dst ,
appending
.Ql \e0
characters if
.Fa src
is less than
.Fa len
characters long, and
.Em not
terminating
.Fa dst
if
.Fa src
is
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.Fa len
or more characters long.
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.Sh RETURN VALUES
The
.Fn strcpy
and
.Fn strncpy
functions
return
.Fa dst .
.Sh EXAMPLES
The following sets
.Dq Li chararray
to
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.Dq Li abc\e0\e0\e0 .
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.Bd -literal -offset indent
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(void)strncpy(chararray, "abc", 6);
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.Ed
.Pp
The following sets
.Dq Li chararray
to
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.Dq Li abcdef
and does
.Em not
null terminate
.Va chararray
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because the source string is \*[Gt]= the length parameter.
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.Fn strncpy
.Em only
null terminates the destination string when the length of the source
string is less than the length parameter.
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.Bd -literal -offset indent
(void)strncpy(chararray, "abcdefgh", 6);
.Ed
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.Pp
The following copies as many characters from
.Va input
to
.Va buf
as will fit and null terminates the result.
Because
.Fn strncpy
does
.Em not
guarantee to null terminate the string itself, we must do this by hand.
.Bd -literal -offset indent
char buf[BUFSIZ];
(void)strncpy(buf, input, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = '\e0';
.Ed
.Pp
Note that
.Xr strlcpy 3
is a better choice for this kind of operation.
The equivalent using
.Xr strlcpy 3
is simply:
.Bd -literal -offset indent
(void)strlcpy(buf, input, sizeof(buf));
.Ed
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.Sh SEE ALSO
.Xr bcopy 3 ,
.Xr memccpy 3 ,
.Xr memcpy 3 ,
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.Xr memmove 3 ,
.Xr strlcpy 3
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.Sh STANDARDS
The
.Fn strcpy
and
.Fn strncpy
functions
conform to
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.St -isoC99 .