Project 6 Dynamic Arrays, More Operator Overloading Solution

Part I The MyString class

Code the MyString class in indicated in the following UML diagram. Note that the member variable is a DYNAMIC ARRAY, so this class will be implementing the Big 3 function (copy constructor, operator= and destructor).




A MyString object is similar to a string object which you have used in Project 5. An object of type MyString will store a collection of characters – a string. Internally, the MyString object will use a char array (c-string) to store the data. This array will be a dynamic array, so that when a MyString object is created, the exact amount of storage needed can be allocated (don’t forget that a c-string stores a ‘\0’ following all chars).




MyString
char * str // storage for characters in the string. This array will contain a ‘\0’ at
//the end so that C-string functions can be used

int len //number of characters in str (not counting the ‘\0’)
+ MyString()

+ MyString(char newstr[])

+ MyString(const MyString& obj) // copy constructor

+ ~MyString() // destructor




+ int getLen() const

+ void setElement(int index, char item)

+ char getElement(int index) const




+ bool operator==(const MyString& obj)

+ bool operator!=(const MyString& obj)

+ char& operator[] (int);

+ MyString& operator=(const MyString& obj) //assignment operator overload

friend ostream& operator<<(ostream& out, const MyString& obj)



MyString() Creates a string which contains “default”;




MyString(char newstr[]) Accepts one C-string argument, allocates

an array large enough for this CString (don’t forget room for the ‘\0’), stores it, and

initializes len




+ MyString(const MyString& obj) This copy constructor initializes the new MyString object

to store the same characters as ‘obj’. The new object is totally independent of the

object ‘obj’ (deep copy)




+ ~MyString() Deletes any dynamic memory that was allocated for this object.




+ int getLen() Returns the number of characters in this string (does not count \0)




//These functions have a precondition that 0 <= in < len

+ void setElement(int in, char item) Sets the character at index ‘in’ to ‘item’

+ char getElement(int in) Returns the character at index ‘in’




+ bool operator==(const MyString& obj) Returns true if this MyString object contains the same

characters (in the same order) as obj




+ bool operator!=(const MyString& obj) Returns true if this MyString object does not contain

the same characters (in the same order) as obj




+ char& operator[] (int in) returns the character at index ‘in’




+ MyString& operator=(const MyString& obj) assignment operator overload

ostream& operator<<(ostream& out, const MyString& obj) non-member function which outputs

all characters MyString object obj





Part II Application

Write an application which:

//tests simple constructors

Creates a MyString object, str1, using the no-arg constructor

Creates a MyString object, str2, using on-arg constructor (user provides string to be passed as argument)

Updates each of the characters of str1, allowing user to enter characters and position

Outputs str1 and str2




// tests simple operator overloads

Outputs a message indicating if str1 and str2 are equal or not

Outputs the characters of str2, one per line (use the [] to access chars)




//tests copy constructor, verifying object independence

Creates a MyString object, str3, initializing it to str2

Output str2 and str3

Updates 2 characters of str2, allowing user to enter characters and position

Output str2 and str3




//tests assignment operator, verifying object independence

Output str1 and str3

Assigns str3 to str1

Output str1 and str3

Updates 2 characters of str3, allowing user to enter characters and position

Output str1 and str3