### 5.29 `strncat`—concatenate strings

Synopsis

         #include <string.h>
         char *strncat(char *restrict dst, const char *restrict src,
             size_t length);

Description
`strncat` appends not more than length characters from the string pointed to by src (including the terminating null character) to the end of the string pointed to by dst. The initial character of src overwrites the null character at the end of dst. A terminating null character is always appended to the result

Warnings
Note that a null is always appended, so that if the copy is limited by the length argument, the number of characters appended to dst is `n + 1`.

Returns
This function returns the initial value of dst

Portability
`strncat` is ANSI C.

`strncat` requires no supporting OS subroutines.