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       strcat, strncat - concatenate two strings


       #include <string.h>

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

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


       The  strcat()  function  appends  the  src  string  to the dest string,
       overwriting the terminating null byte ('\0') at the end  of  dest,  and
       then  adds  a  terminating null byte.  The strings may not overlap, and
       the dest string must have enough space for the result.  If dest is  not
       large  enough, program behavior is unpredictable; buffer overruns are a
       favorite avenue for attacking secure programs.

       The strncat() function is similar, except that

       *  it will use at most n bytes from src; and

       *  src does not need to be null-terminated if it  contains  n  or  more

       As  with  strcat(),  the  resulting  string  in  dest  is  always null-

       If src contains n or more bytes, strncat() writes n+1 bytes to dest  (n
       from  src plus the terminating null byte).  Therefore, the size of dest
       must be at least strlen(dest)+n+1.

       A simple implementation of strncat() might be:

           char *
           strncat(char *dest, const char *src, size_t n)
               size_t dest_len = strlen(dest);
               size_t i;

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

               return dest;


       The strcat() and strncat() functions return a pointer to the  resulting
       string dest.


       For   an   explanation   of   the  terms  used  in  this  section,  see

       │InterfaceAttributeValue   │
       │strcat(), strncat() │ Thread safety │ MT-Safe │


       POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.


       Some systems (the BSDs, Solaris,  and  others)  provide  the  following

           size_t strlcat(char *dest, const char *src, size_t size);

       This  function  appends  the  null-terminated  string src to the string
       dest,  copying  at  most  size-strlen(dest)-1  from  src,  and  adds  a
       terminating  null  byte  to  the  result,  unless  size  is  less  than
       strlen(dest).  This  function  fixes  the  buffer  overrun  problem  of
       strcat(), but the caller must still handle the possibility of data loss
       if size is too small.  The function returns the length  of  the  string
       strlcat() tried to create; if the return value is greater than or equal
       to size, data loss occurred.  If data loss  matters,  the  caller  must
       either check the arguments before the call, or test the function return
       value.  strlcat() is not present in glibc and is  not  standardized  by
       POSIX, but is available on Linux via the libbsd library.


       bcopy(3),  memccpy(3),  memcpy(3),  strcpy(3),  string(3),  strncpy(3),
       wcscat(3), wcsncat(3)


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