Implement the interface from mystring.h using dyamically$-$allocated

strings that will allocate exactly the correct amount of memory to store their

characters. But they will also have an arbitrary maximum length of

MAX$\_$STRING$\_$LENGTH, which will be defined elsewhere.

Assume the code you write will be saved to mystring.c; write the complete

contents of that file. Implement only the data structure; do not write a main

program. Write appropriate contracts.$//$ This is an interface for a string data type.

$//$ A string stores an exactly$-$sized, immutable string.

typedef struct STRING String;

$//$ This is the maximum length of a string.

$//$ It is application$-$specific and will not be defined in mystring.c$.$

$//$ Instead, it will be defined by the program that uses this interface.

extern const int MAX$\_$STRING$\_$LENGTH;

$//$ Create and return a new string containing a copy of the string "init".

$//$ Allocate exactly as many characters as needed to store it$.$

$//$ Return NULL on error, such as init is longer than MAX$\_$STRING$\_$LENGTH.

String $*$ new$\_$string$($ char $*$init $)$;

$//$ Destroy the string, freeing all of its memory.

void destroy$\_$string$($ String $*$the$\_$string$)$;

$//$ Create and return a new string containing the concatenation $($joining$)$

$//$ of stringl and string $2,$ again allocating exactly as many characters as

$//$ required. Return NULL on error.

String $*$ concat $($ String $*$string$1,$ String $*$string$2)$;

$//$ Copy up to "max$\_$len" chars and $10$ from the string to the given char "array".

$//$ The "max$\_$len" includes $10,$ which will always be placed at the end.

$//$ Return the number of characters copied excluding $10,$ or $-1$ on error.

int to$\_$array$($ String $*$string$,$ char $*$array$,$ int max$\_$len $)$;