Documentation Archive Developer
ADC Home > Reference Library > Reference > Mac OS X > Mac OS X Man Pages


This document is a Mac OS X manual page. Manual pages are a command-line technology for providing documentation. You can view these manual pages locally using the man(1) command. These manual pages come from many different sources, and thus, have a variety of writing styles.

For more information about the manual page format, see the manual page for manpages(5).

STRCPY(3)                BSD Library Functions Manual                STRCPY(3)

     stpcpy, strcpy, strncpy -- copy strings

     Standard C Library (libc, -lc)

     #include <string.h>

     char *
     stpcpy(char *s1, const char *s2);

     char *
     strcpy(char *restrict s1, const char *restrict s2);

     char *
     strncpy(char *restrict s1, const char *restrict s2, size_t n);

     The stpcpy() and strcpy() functions copy the string s2 to s1 (including
     the terminating `\0' character).

     The strncpy() function copies at most n characters from s2 into s1.  If
     s2 is less than n characters long, the remainder of s1 is filled with
     `\0' characters.  Otherwise, s1 is not terminated.

     The strcpy() and strncpy() functions return s1.  The stpcpy() function
     returns a pointer to the terminating `\0' character of s1.

     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

           (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 malicious
     cious users to arbitrarily change a running program's functionality
     through a buffer overflow attack.  (See the FSA and EXAMPLES.)

     bcopy(3), memccpy(3), memcpy(3), memmove(3), strlcpy(3)

     The strcpy() and strncpy() functions conform to ISO/IEC 9899:1990
     (``ISO C90'').  The stpcpy() function is an MS-DOS and GNUism.  The
     stpcpy() function conforms to no standard.

     The stpcpy() function first appeared in FreeBSD 4.4, coming from
     1998-vintage Linux.

BSD                             August 9, 2001                             BSD