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NAME

       strcpy, strncpy - copy a string

SYNOPSIS

       #include <string.h>

       char *strcpy(char *dest, const char *src);

       char *strncpy(char *dest, const char *src, size_t n);

DESCRIPTION

       The  strcpy() function copies the string pointed to by src, including the terminating null
       byte ('\0'), to the buffer pointed to by dest.  The  strings  may  not  overlap,  and  the
       destination string dest must be large enough to receive the copy.

       The  strncpy()  function  is  similar,  except  that  at  most  n bytes of src are copied.
       Warning: If there is no null byte among the first n bytes of src,  the  string  placed  in
       dest will not be null-terminated.

       If the length of src is less than n, strncpy() pads the remainder of dest with null bytes.

       A simple implementation of strncpy() might be:

           char *
           strncpy(char *dest, const char *src, size_t n)
           {
               size_t i;

               for (i = 0; i < n && src[i] != '\0'; i++)
                   dest[i] = src[i];
               for ( ; i < n; i++)
                   dest[i] = '\0';

               return dest;
           }

RETURN VALUE

       The strcpy() and strncpy() functions return a pointer to the destination string dest.

CONFORMING TO

       SVr4, 4.3BSD, C89, C99.

NOTES

       Some  programmers consider strncpy() to be inefficient and error prone.  If the programmer
       knows (i.e., includes code to test!)  that the size of dest is greater than the length  of
       src, then strcpy() can be used.

       If  there is no terminating null byte in the first n characters of src, strncpy() produces
       an unterminated string in  dest.   Programmers  often  prevent  this  mistake  by  forcing
       termination as follows:

           strncpy(buf, str, n);
           if (n > 0)
               buf[n - 1]= '\0';

BUGS

       If  the  destination string of a strcpy() is not large enough, then anything might happen.
       Overflowing fixed-length string  buffers  is  a  favorite  cracker  technique  for  taking
       complete  control  of the machine.  Any time a program reads or copies data into a buffer,
       the program first needs to check that there's enough space.  This may  be  unnecessary  if
       you  can  show  that overflow is impossible, but be careful: programs can get changed over
       time, in ways that may make the impossible possible.

SEE ALSO

       bcopy(3), memccpy(3), memcpy(3), memmove(3), stpcpy(3), stpncpy(3), strdup(3),  string(3),
       wcscpy(3), wcsncpy(3)

COLOPHON

       This  page  is  part of release 3.35 of the Linux man-pages project.  A description of the
       project, and information about reporting bugs, can be found at  http://man7.org/linux/man-
       pages/.