In this assignment, you will provide one possible implementation of the string class. You

will use a dynamic array of characters to represent the string. In order to avoid conflicts, we

will call the class myString and use the file names myString.h and myString.cc$.($There

are better ways to avoid conflicts, and we will discuss this later in the course.$)$

Functionalities

Your class should provide the following methods. Here, $$current string$$ refers to the string

that the method is called with. I.e$.$ in s$.$length$(),$ s is the $$current string.$$

$$ default constructor: initializes to the empty string.

$$ a constructor with a char $*$ parameter $($i$.$e$.$ conversion$).$ The supplied pointer should

be treated as a character array. The string should be initialized to the content of

the character array until the character $\backslash 0$ is seen. This is called a $$null$-$terminated

string$$ or a $$C$-$string.$$ Note that a string literal in C$++($e$.$g$.$ "hello"$)$ is treated as

a character array.

$$ a constructor with a char parameter $($i$.$e$.$ conversion$).$ A string with a single character

is constructed.

$$ a copy constructor and an assignment operator.

$$ a destructor.

$$ int length$()$: returns the length of the string.

$$ char& at$($int i$)$: returns a reference to the ith character. Also provide a version

which returns a reference to a constant.

$$ myString substr$($int k$,$ int n$)$: returns a substring of the current string starting

at index k and of length n$.$ E$.$g$.$ If s $==$ "abcdefg", then s$.$substr$(2,4)==$ "cdef".

$1$

$$ myString& erase$($int k$,$ int n$)$: erase n characters starting at index k from the

current string. Returns a reference to the modified string. E$.$g$.$ If s $==$ "abcdefg",

then after s$.$erase$(2,4),$ s $==$ "abg".

$$ myString& insert$($int k$,$ const myString& s$)$: inserts the string s into the current

string at position k$.$ Returns a reference to the modified string. E$.$g$.$ If s $==$

"abcdefg", then after s$.$insert$(2,"$xyz$"),$ s $==$ "abxyzcdefg". Here, k can be the

length of the string, meaning that the string s is appended to the current string.

$$ int find$($const myString& s$)$: returns the index to the first occurrence of the string

s inside the current string. If s does not occur in the current string, the function returns

myString::npos $($see notes below$).$

Also, provide the following friend functions:

$$ istream& getline$($istream& is$,$ myString& s$)$: reads a line of text into a string.

Notes

$1.$ This is a large class. You may want to implement a few functionalities at a time and

test them. START EARLY!

$2.$ Your assignment will be marked on program correctness and readability $($including

comments$).$ For all classes, use const member functions when appropriate. When

appropriate, use assert to ensure that the supplied indices are correct. You may wish

to write private helper functions for certain tasks, such as resizing the array, copying

the array, etc.

$3.$ Also write a Makefile which can be used to compile all programs in this assignment.

$4.$ The constant myString::npos should be a static constant member set to $1.$ It is

guaranteed to be an invalid index into the string.

$5.$ A driver program $($stringTest$.$cc$)$ will be provided to you to test your string class.

$6.$ Be sure that there are no memory errors: all arrays are large enough to hold the results,

and there are no memory leaks.

$7.$ The standard way of using dynamic arrays $($allocating an array just large enough to

hold the result and remembering its size$)$ can be inefficient because of the frequent

need to allocate and deallocate arrays. In this assignment, we are not concerned about

efficiency.

$2$