NetBSD/lib/libc/string/strcpy.3

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.\"     from: @(#)strcpy.3	8.1 (Berkeley) 6/4/93
.\"	$NetBSD: strcpy.3,v 1.14 2003/05/06 10:10:41 wiz Exp $
.\"
.Dd May 6, 2002
.Dt STRCPY 3
.Os
.Sh NAME
.Nm strcpy ,
.Nm strncpy
.Nd copy strings
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In string.h
.Ft char *
.Fn strcpy "char * restrict dst" "const char * restrict src"
.Ft char *
.Fn strncpy "char * restrict dst" "const char * restrict src" "size_t len"
.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
.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
.Fa len
or more characters long.
.Sh RETURN VALUES
The
.Fn strcpy
and
.Fn strncpy
functions
return
.Fa dst .
.Sh EXAMPLES
The following sets
.Dq Li chararray
to
.Dq Li abc\e0\e0\e0 .
.Bd -literal -offset indent
(void)strncpy(chararray, "abc", 6);
.Ed
.Pp
The following sets
.Dq Li chararray
to
.Dq Li abcdef
and does
.Em not
null terminate
.Va chararray
because the source string is \*[Gt]= the length parameter.
.Fn strncpy
.Em only
null terminates the destination string when the length of the source
string is less than the length parameter.
.Bd -literal -offset indent
(void)strncpy(chararray, "abcdefgh", 6);
.Ed
.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
.Sh SEE ALSO
.Xr bcopy 3 ,
.Xr memccpy 3 ,
.Xr memcpy 3 ,
.Xr memmove 3 ,
.Xr strlcpy 3
.Sh STANDARDS
The
.Fn strcpy
and
.Fn strncpy
functions
conform to
.St -isoC99 .