Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
STRCPY(3)		 BSD Library Functions Manual		     STRCPY(3)

NAME
     stpcpy, stpncpy, strcpy, strncpy -- copy strings

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <string.h>

     char *
     stpcpy(char * restrict dst, const char * restrict src);

     char *
     stpncpy(char * restrict dst, const	char * restrict	src, size_t len);

     char *
     strcpy(char * restrict dst, const char * restrict src);

     char *
     strncpy(char * restrict dst, const	char * restrict	src, size_t len);

DESCRIPTION
     The strcpy() and stpcpy() functions copy the string src to	dst (including
     the terminating `\0' character.)

     The strncpy() and stpncpy() functions copy	at most	len characters from
     src into dst.  If src is less than	len characters long, the remainder of
     dst is filled with	`\0' characters.  Otherwise, dst is not	terminated.

     For all of	strcpy(), strncpy(), stpcpy(), and stpncpy(), the result is
     undefined if src and dst overlap.

RETURN VALUES
     The strcpy() and strncpy()	functions return dst.  The stpcpy() and
     stpncpy() functions return	a pointer to the terminating `\0' character of
     dst.  If stpncpy()	does not terminate dst with a NUL character, it	in-
     stead returns a pointer to	dst[n] (which does not necessarily refer to a
     valid memory location.)

EXAMPLES
     The following sets	chararray to "abc\0\0\0":

	   char	chararray[6];

	   (void)strncpy(chararray, "abc", sizeof(chararray));

     The following sets	chararray to "abcdef":

	   char	chararray[6];

	   (void)strncpy(chararray, "abcdefgh",	sizeof(chararray));

     Note that it does not NUL terminate chararray because the length of the
     source string is greater than or equal to the length argument.

     The following copies as many characters from input	to buf as will fit and
     NUL terminates the	result.	 Because strncpy() does	not guarantee to NUL
     terminate the string itself, this must be done explicitly.

	   char	buf[1024];

	   (void)strncpy(buf, input, sizeof(buf) - 1);
	   buf[sizeof(buf) - 1]	= '\0';

     This could	be better achieved using strlcpy(3), as	shown in the following
     example:

	   (void)strlcpy(buf, input, sizeof(buf));

SEE ALSO
     bcopy(3), memccpy(3), memcpy(3), memmove(3), strlcpy(3), wcscpy(3)

STANDARDS
     The strcpy() and strncpy()	functions conform to ISO/IEC 9899:1990
     ("ISO C90").  The stpcpy()	and stpncpy() functions	conform	to IEEE	Std
     1003.1-2008 ("POSIX.1").

HISTORY
     The stpcpy() function first appeared in FreeBSD 4.4, and stpncpy()	was
     added in FreeBSD 8.0.

SECURITY CONSIDERATIONS
     All of the	functions documented in	this manual page are easily misused in
     a manner which enables malicious users to arbitrarily change a running
     program's functionality through a buffer overflow attack.

     It	is strongly suggested that the strlcpy() function be used in almost
     all cases.

     For some, but not all, fixed-length records, non-terminated strings may
     be	both valid and desirable.  In that specific case, the strncpy()	func-
     tion may be most sensible.

BSD				 June 6, 2018				   BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | EXAMPLES | SEE ALSO | STANDARDS | HISTORY | SECURITY CONSIDERATIONS

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=stpcpy&sektion=3&manpath=FreeBSD+13.0-RELEASE+and+Ports>

home | help