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 *dst, const char *src);
 char *
 stpncpy(char *restrict dst, const char *restrict src, size_t n);
 char *
 strcpy(char *restrict dst, const char *restrict src);
 char *
 strncpy(char *restrict dst, const char *restrict src, size_t n);

DESCRIPTION

 The stpcpy() and strcpy() functions copy the string src to dst (including
 the terminating `0円' character).
 The stpncpy() and strncpy() functions copy at most n characters from src
 into dst. If src is less than n characters long, the remainder of dst is
 filled with `0円' characters. Otherwise, dst is not terminated.
 The source and destination strings should not overlap, as the behavior is
 undefined.

RETURN VALUES

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

EXAMPLES

 The following sets chararray to ``abc0円0円0円'':
 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円';
 This could be better achieved using strlcpy(3) , as shown in the following
 example:
 (void)strlcpy(buf, input, sizeof(buf));

SECURITY CONSIDERATIONS

 The strcpy(), strncpy(), stpcpy(), and stpncpy() functions are easily
 misused in a manner which enables malicious users to arbitrarily change a
 running program's functionality through a buffer overflow attack. (See
 the FSA and EXAMPLES.)
 It is recommended that strlcpy(3)  be used instead as a way to avoid such
 problems. strlcpy(3)  is not defined in any standards, but it has been
 adopted by most major libc implementations.

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 .

HISTORY

 The stpcpy() function first appeared in FreeBSD 4.4, and stpncpy() was
 added in FreeBSD 8.0.
BSD February 28, 2009 BSD