STRCPY(3) BSD Library Functions Manual STRCPY(3)NAME
stpcpy, stpncpy, strcpy, strncpy — copy strings
Standard C Library (libc, -lc)
stpcpy(char * restrict dst, const char * restrict src);
stpncpy(char * restrict dst, const char * restrict src, size_t len);
strcpy(char * restrict dst, const char * restrict src);
strncpy(char * restrict dst, const char * restrict src, size_t len);
The stpcpy() and strcpy() functions copy the string src to dst (including
the terminating ‘\0’ character.)
The stpncpy() and strncpy() 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.
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
instead returns a pointer to dst[n] (which does not necessarily refer to
a valid memory location.)
The following sets chararray to “abc\0\0\0”:
(void)strncpy(chararray, "abc", sizeof(chararray));
The following sets chararray to “abcdef”:
(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.
(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
(void)strlcpy(buf, input, sizeof(buf));
Note that because strlcpy(3) is not defined in any standards, it should
only be used when portability is not a concern.
The strcpy() function is easily misused in a manner which enables mali‐
cious users to arbitrarily change a running program's functionality
through a buffer overflow attack. (See the FSA and EXAMPLES.)
SEE ALSObcopy(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
The stpcpy() function first appeared in FreeBSD 4.4, and stpncpy() was
added in FreeBSD 8.0.
BSD February 28, 2009 BSD