C++ Dynamic Memory Program

This week you'll be making the following refinements to the class that you wrote in the last assignment. All the requirements from that class are still in force. For example, all MyStrings must always be stored in a dynamic array that is exactly the correct size to store the string. Your score on this assignment will take into consideration your work on both the previous assignment and this assignment.

1. Extraction Operator

Just like the >> operator that reads C-strings, your >> operator should skip any leading spaces and then read characters into the string up to the first whitespace character.

For reasons of convenience, we will impose a limit of 127 on the number of characters this function will read. This is so you can temporarily read into a non-dynamic array and then copy what you need into your data member, which will be a dynamic array. Note that this does not mean that all MyStrings will always have a maximum of 127 characters. For example, you might get a MyString with more than 127 characters by using the MyString constructor or by concatenating two MyStrings.

Hint: Don't try to read character by character in a loop. Use the extraction operator to do the reading of the input into a non-dynamic array, then use strcpy() to copy it into your data member. Make sure to allocate the correct amount of memory.

Hint: if you use the extraction operator as suggested above, you will not have to skip leading whitespace, because the extraction operator does that for you.

2. A read() function

The read() function will allow the client programmer to specify the delimiting character (the character at which reading will stop). It should work just like the getline() function works for c-strings; that is, it should place everything up to but not including the delimiting character into the calling object, and it should also consume (and discard) the delimiting character. This will be a void function that will take two arguments, a stream and the delimiting character. It should not skip leading spaces. The limit of 127 characters imposed on the >> function above also applies to this function.

Hint: Don't try to read character by character in a loop. Use the in.getline() function to do the reading of the input into a non-dynamic array, then use strcpy() to copy it into your data member.

3. Concatenation Operator

Overload the + operator to do MyString concatenation. The operator must be able to handle either MyString objects or C-strings on either side of the operator. Be careful with the memory management here. You'll have to allocate enough memory to hold the new MyString. I suggest using strcpy() to get the left operand into the result MyString, and then strcat() to append the right operand. Both strcpy() and strcat() should be used as if they are void, even though they do have return values.

4. Combined Concatenation/Assignment Operator

Overload the shorthand += to combine concatenation and assignment. Only MyStrings can be on the left-hand side of a += operation, but either MyStrings or C-strings may appear on the right side. If you pay close attention to the += operator from the feetInches class, these may be the easiest points of the semester.

5. Add Documentation

Hints about reading input files:

I suggest that you copy the text from the input file webpage(s) and paste it into a file that you have created using your IDE. The files you create when you type in your IDE are always text files (even if they don't end with .txt). If you're using Windows, you could also use Notepad, but there's no reason to open another application when you are already working in your IDE. I strongly suggest that you don't use TextEdit (Mac) or Word, because these do not store files as text files by default.

Client File:

/* * ------------------- * These functions are designed to help you test your MyString objects, * as well as show the client usage of the class. * * The BasicTest function builds an array of strings using various * constructor options and prints them out. It also uses the String * stream operations to read some strings from a data file. * * The RelationTest function checks out the basic relational operations * (==, !=, <, etc) on Strings and char *s. * * The ConcatTest functions checks the overloaded + and += operators that * do string concatenation. * * The CopyTest tries out the copy constructor and assignment operators * to make sure they do a true deep copy. * * Although not exhaustive, these tests will help you to exercise the basic * functionality of the class and show you how a client might use it. * * While you are developing your MyString class, you might find it * easier to comment out functions you are ready for, so that you don't * get lots of compile/link complaints. */ #include "mystring.h" #include  #include  // for toupper() #include  #include  #include  using namespace std; using namespace cs_mystring; void BasicTest(); void RelationTest(); void ConcatTest(); void CopyTest(); MyString AppendTest(const MyString& ref, MyString val); string boolString(bool convertMe); int main() { BasicTest(); RelationTest(); ConcatTest(); CopyTest(); } string boolString(bool convertMe) { if (convertMe) { return "true"; } else { return "false"; } } void BasicTest() { MyString s; int stringLength; cout << "----- Testing basic String creation & printing" << endl; const MyString strs[] = {MyString("Wow"), MyString("C++ is neat!"), MyString(""), MyString("a-z")}; for (int i = 0; i < 4; i++){ cout << "string [" << i <<"] = " << strs[i] << endl; } cout << endl << "----- Now reading MyStrings from file" << endl; cout << endl << "----- first, word by word" << endl; ifstream in("mystring.txt"); assert(in); while (in.peek() == '#'){ in.ignore(128, ' '); } in >> s; while (in) { cout << "Read string = " << s << endl; in >> s; } in.close(); cout << endl << "----- now, line by line" << endl; ifstream in2("mystring.txt"); assert(in2); while (in2.peek() == '#'){ in2.ignore(128, ' '); } s.read(in2, ' '); while (in2) { cout << "Read string = " << s << endl; s.read(in2, ' '); } cout << endl << "----- Testing access to characters (using const)" << endl; const MyString s1("abcdefghijklmnopqsrtuvwxyz"); cout << "Whole string is " << s1 << endl; cout << "now char by char: "; stringLength = s1.length(); for (int i = 0; i < stringLength; i++){ cout << s1[i]; } cout << endl << "----- Testing access to characters (using non-const)" << endl; MyString s2("abcdefghijklmnopqsrtuvwxyz"); cout << "Start with " << s2; stringLength = s2.length(); for (int i = 0; i < stringLength; i++){ s2[i] = toupper(s2[i]); } cout << " and convert to " << s2 << endl; } void RelationTest() { cout << " ----- Testing relational operators between MyStrings "; const MyString strs[] = {MyString("app"), MyString("apple"), MyString(""), MyString("Banana"), MyString("Banana")}; for (int i = 0; i < 4; i++) { cout << "Comparing " << strs[i] << " to " << strs[i+1] << endl; cout << "\tIs left < right? " << boolString(strs[i] < strs[i+1]) << endl; cout << "\tIs left <= right? " << boolString(strs[i] <= strs[i+1]) << endl; cout << "\tIs left > right? " << boolString(strs[i] > strs[i+1]) << endl; cout << "\tIs left >= right? " << boolString(strs[i] >= strs[i+1]) << endl; cout << "\tDoes left == right? " << boolString(strs[i] == strs[i+1]) << endl; cout << "\tDoes left != right ? " << boolString(strs[i] != strs[i+1]) << endl; } cout << " ----- Testing relations between MyStrings and char * "; MyString s("he"); const char *t = "hello"; cout << "Comparing " << s << " to " << t << endl; cout << "\tIs left < right? " << boolString(s < t) << endl; cout << "\tIs left <= right? " << boolString(s <= t) << endl; cout << "\tIs left > right? " << boolString(s > t) << endl; cout << "\tIs left >= right? " << boolString(s >= t) << endl; cout << "\tDoes left == right? " << boolString(s == t) << endl; cout << "\tDoes left != right ? " << boolString(s != t) << endl; MyString u("wackity"); const char *v = "why"; cout << "Comparing " << v << " to " << u << endl; cout << "\tIs left < right? " << boolString(v < u) << endl; cout << "\tIs left <= right? " << boolString(v <= u) << endl; cout << "\tIs left > right? " << boolString(v > u) << endl; cout << "\tIs left >= right? " << boolString(v >= u) << endl; cout << "\tDoes left == right? " << boolString(v == u) << endl; cout << "\tDoes left != right ? " << boolString(v != u) << endl; } void ConcatTest() { cout << " ----- Testing concatentation on MyStrings "; const MyString s[] = {MyString("outrageous"), MyString("milk"), MyString(""), MyString("cow"), MyString("bell")}; for (int i = 0; i < 4; i++) { cout << s[i] << " + " << s[i+1] << " = " << s[i] + s[i+1] << endl; } cout << " ----- Testing concatentation between MyString and char * "; const MyString a("abcde"); const char *b = "XYZ"; cout << a << " + " << b << " = " << a + b << endl; cout << b << " + " << a << " = " << b + a << endl; cout << " ----- Testing shorthand concat/assign on MyStrings "; MyString s2[] = {MyString("who"), MyString("what"), MyString("WHEN"), MyString("Where"), MyString("why")}; for (int i = 0; i < 4; i++) { cout << s2[i] << " += " << s2[i+1] << " = "; cout << (s2[i] += s2[i+1]) << "and"; cout << s2[i] << endl; } cout << " ----- Testing shorthand concat/assign using char * "; MyString u("I love "); const char *v = "programming"; cout << u << " += " << v << " = "; cout << (u += v) << endl; } MyString AppendTest(const MyString& ref, MyString val) { val[0] = 'B'; return val + ref; } void CopyTest() { cout << " ----- Testing copy constructor and operator= on MyStrings "; MyString orig("cake"); MyString copy(orig); // invoke copy constructor copy[0] = 'f'; // change first letter of the *copy* cout << "original is " << orig << ", copy is " << copy << endl; MyString copy2; // makes an empty string copy2 = orig; // invoke operator= copy2[0] = 'f'; // change first letter of the *copy* cout << "original is " << orig << ", copy is " << copy2 << endl; copy2 = "Copy Cat"; copy2 = copy2; // copy onto self and see what happens cout << "after self assignment, copy is " << copy2 << endl; cout << "Testing pass & return MyStrings by value and ref" << endl; MyString val = "winky"; MyString sum = AppendTest("Boo", val); cout << "after calling Append, sum is " << sum << endl; cout << "val is " << val << endl; val = sum; cout << "after assign, val is " << val << endl; } 

Date File:

# This file has some strings that are used in the string test to check # reading strings from files. The default overloaded >> of your string # class should skip over any leading spaces and read characters into # the string object, stopping at the first whitespace character (this is # similar to the behavior of >> on char *). The read method of the # string class is a little fancier. It allows client to restrict # how many characters at max to read and what character to use as # delimiter, so you can stop at newline instead of space, for example. # Reading consumes the delimiting character, so the next read starts # after that. # The first time we will read individual words, next we read whole lines 

Correct Output:

----- Testing basic String creation & printing string [0] = Wow string [1] = C++ is neat! string [2] = string [3] = a-z ----- Now reading MyStrings from file ----- first, word by word Read string = The Read string = first Read string = time Read string = we Read string = will Read string = read Read string = individual Read string = words, Read string = next Read string = we Read string = read Read string = whole Read string = lines ----- now, line by line Read string = The first time we will Read string = read individual words, next Read string = we read whole lines ----- Testing access to characters (using const) Whole string is abcdefghijklmnopqsrtuvwxyz now char by char: abcdefghijklmnopqsrtuvwxyz ----- Testing access to characters (using non-const) Start with abcdefghijklmnopqsrtuvwxyz and convert to ABCDEFGHIJKLMNOPQSRTUVWXYZ ----- Testing relational operators between MyStrings Comparing app to apple Is left < right? true Is left <= right? true Is left > right? false Is left >= right? false Does left == right? false Does left != right ? true Comparing apple to Is left < right? false Is left <= right? false Is left > right? true Is left >= right? true Does left == right? false Does left != right ? true Comparing to Banana Is left < right? true Is left <= right? true Is left > right? false Is left >= right? false Does left == right? false Does left != right ? true Comparing Banana to Banana Is left < right? false Is left <= right? true Is left > right? false Is left >= right? true Does left == right? true Does left != right ? false ----- Testing relations between MyStrings and char * Comparing he to hello Is left < right? true Is left <= right? true Is left > right? false Is left >= right? false Does left == right? false Does left != right ? true Comparing why to wackity Is left < right? false Is left <= right? false Is left > right? true Is left >= right? true Does left == right? false Does left != right ? true ----- Testing concatentation on MyStrings outrageous + milk = outrageousmilk milk + = milk + cow = cow cow + bell = cowbell ----- Testing concatentation between MyString and char * abcde + XYZ = abcdeXYZ XYZ + abcde = XYZabcde ----- Testing shorthand concat/assign on MyStrings who += what = whowhatandwhowhat what += WHEN = whatWHENandwhatWHEN WHEN += Where = WHENWhereandWHENWhere Where += why = WherewhyandWherewhy ----- Testing shorthand concat/assign using char * I love += programming = I love programming ----- Testing copy constructor and operator= on MyStrings original is cake, copy is fake original is cake, copy is fake after self assignment, copy is Copy Cat Testing pass & return MyStrings by value and ref after calling Append, sum is BinkyBoo val is winky after assign, val is BinkyBoo 

//mystring.h file to edit

#ifndef myString_H

#define myString_H

#include

using namespace std;

namespace cs_mystring {

class MyString {

public:

//DEFAULT CONSTRUCTOR

MyString();

//Preconditon: Takes no parameter and return nothing..not even void

//Postcondition: initialize data member-'desc' with memory of size 1 and copy empty string to it

//CONSTRUCTOR

MyString(const char *inDesc);

//Preconditon: Takes one argument - pointer to char object 'inDesc' and is kept const

//Postcondition: object is created with size accordingly with specified object pointer given at input

//COPY CONSTRUCTOR

MyString(const MyString& right);

//Preconditon: Takes one argument - reference to MyString object 'right' and is kept const

//Postcondition: object is created with size accordingly with specified object reference given at input

//DESTRUCTOR

~MyString();

//Preconditon: an MyString object exist with valid length

//Postcondition: MyString object is destroyed

//ASSIGNMENT OPERATOR

MyString operator=(const MyString& right);

//Preconditon: Input argument contains address to MyString object:-Right.

//Postcondition: object is copied with size accordingly with specified object reference given at input

// CONCAT/ASSIGNMENT OPERATOR

MyString operator+=(const MyString& right);

//Preconditon: Input argument contains address to MyString object:-Right.

//Postcondition: returns pointer to this object which was created by combination of concatenation and assignment operator

MyString operator+=(const char *right);

//Preconditon: Input argument contains pointer to char object:-Right.

//Postcondition: returns pointer to this char object which was created by combination of concatenation and assignment operator

int length() const;

//Preconditon: length donot take any argument

//Postcondition: returns length of MyString object

// OVERLOADING THE EXTRACTION OPERATOR

friend ostream& operator<<(ostream& out, const MyString& source);

//Precondition: The out of ostream object is waiting to receive the MyString output.

//Postcondition: MyString source has been passed by reference to the ostream out and is kept const.

//OVERLOADED INSERTION OPERATOR

friend istream& operator>>(istream& in, MyString &source);

//Precondition: The in of istream object is waiting to receive the MyString input.

//Postcondition: MyString source has been passed by reference into the istream 'in'.

//OVERLOADED All SIX OF THE RELATIONAL OPERATOR (<, <=, >, >=, ==, !=)

friend bool operator<(const MyString &Left, const MyString &Right);

//Precondition:- Input argument contains address to two MyString object:- Left and Right.

//Postcondition: function return's true, if Left < Right, else it return's false.

friend bool operator<=(const MyString &Left, const MyString &Right);

//Precondition:- Input parameters contains reference to two MyString object:- Left and Right.

//Postcondition: function return's true, if Left <= Right, else it return's false.

friend bool operator==(const MyString &Left, const MyString &Right);

//Precondition:- Input parameters contains reference to two MyString object:- Left and Right.

//Postcondition: function return's true, if Left == Right, else it return's false.

friend bool operator!=(const MyString &Left, const MyString &Right);

//Precondition:- Input parameters contains reference to two MyString object:- Left and Right.

//Postcondition: function return's true, if Left != Right, else it return's false.

friend bool operator>=(const MyString &Left, const MyString &Right);

//Precondition:- Input parameters contains reference to two MyString object:- Left and Right.

//Postcondition: function return's true, if Left >= Right, else it return's false.

friend bool operator>(const MyString &Left, const MyString &Right);

//Precondition:- Input parameters contains reference to two MyString object:- Left and Right.

//Postcondition: function return's true, if Left > Right, else it return's false.

//READ FROM FILE

void read(istream& inString, char delim);

//Preconditon: Input argument contains two argument, a stream and the delimiting character.

//Postcondition: Reads character by character in a loop. Use the in.getline() function to do the reading of the input into a non-dynamic array, then use strcpy() to copy it into your data member. return void.

//CONCAT OPERATOR

friend const MyString operator+(const MyString &left, const MyString &right);

//Precondition:- Input parameters contains reference to two MyString object:- Left and Right.

//Postcondition: function return's addition of two MyString objects.

// OVERLOADING THE SQUARE BRACKETS

char operator[](int index) const;

//Preconditon: Input argument contains value of index.

//Postcondition: Returns the index to MyString specifying the char to that location which is const.

char& operator[](int index);

//Preconditon: Input argument contains value of index.

//Postcondition: Returns the index to MyString specifying the char to that location.

private:

char *desc; //POINTER DATA MEMBER

};

}

#endif

//mystring.cpp to edit

#include

#include

#include "MyString.h"

using namespace std;

namespace cs_mystring {

/*Default construtor takes no parameter : initialize desc with memory of size 1 and copy empty string to it.*/

MyString::MyString() {

desc = new char[1];

strcpy(desc, "");

}

/*The parameterized constructor takes pointer argument pointing to the object. First create space to copy object to at 'desc' a private member data. and then copy to destination. The memory created is equal to object length + 1.*/

MyString::MyString(const char *inDesc) {

desc = new char[strlen(inDesc) + 1];

strcpy(desc, inDesc);

}

/*The parameterized construtor takes one reference parameter the address to the object location. First create space to copy object to at 'desc' a private member data. and then copy to destination. The memory created is equal to object length + 1.*/

MyString::MyString(const MyString& right) {

desc = new char[strlen(right.desc) + 1];

strcpy(desc, right.desc);

}

//Destructor is written to destroy object of whatever length

MyString::~MyString() {

delete[] desc;

}

/* The overloaded operator = , takes one argument reference to object and is kept const. first we free memory of private data member desc, then assign memory of appropriate length according to size of object reference. Later copy object of specified length to private data member and return pointer to object. */

MyString MyString::operator=(const MyString& right) {

if (this != &right) {

delete[] desc;

desc = new char[strlen(right.desc) + 1];

strcpy(desc, right.desc);

}

return *this;

}

/*Overloaded operator == function contains addresses of two valid MyString:- left and right. strcmp function compares. It return's true, on when left.desc and right.desc == 0*/

bool operator==(const MyString& left, const MyString& right) {

return strcmp(left.desc, right.desc) == 0;

}

/*Overloaded operator < function contains addresses of two valid MyString:- left and right. strcmp function compares. It return's true, on when left.desc and right.desc < 0*/

bool operator<(const MyString& left, const MyString& right) {

return strcmp(left.desc, right.desc) < 0;

}

/*Overloaded operator != function contains addresses of two valid MyString:- left and right. It return's true, on when left is not equal right */

bool operator!=(const MyString& left, const MyString& right) {

return !(left == right);

}

/*Overloaded operator > function contains addresses of two valid MyString:- left and right. It return's true, on when left is not equal right and is not less than right*/

bool operator>(const MyString& left, const MyString& right) {

return !(left == right) && !(left < right);

}

/*Overloaded operator <= function contains addresses of two valid MyString:- left and right. It return's true, on when left is less than right or equals to right*/

bool operator<=(const MyString& left, const MyString& right) {

return left < right || left == right;

}

/*Overloaded operator >= function contains addresses of two valid MyString:- left and right. It return's true, on when left is not less than right*/

bool operator>=(const MyString& left, const MyString& right) {

return !(left < right);

}

// return length of string in int

int MyString::length() const {

return (int)strlen(desc);

}

/*Overloaded operator << function takes computed address of source and is passed to out object of ostream to display results.*/

ostream& operator<<(ostream& out, const MyString& source) {

out << source.desc;

return out;

}

/* Overloading The Square Brackets returns a const char for the index returned. Its operator takes index and use assert to check whether the index falls is >= 0 and index is < string length. If it does then return the index to MyString specifying the char to that index.*/

char MyString::operator[](int index) const {

assert(index >= 0 && index < strlen(desc));

return desc[index];

}

/* Overloading The Square Brackets returns an reference to char at that index. Its operator takes index and use assert to check whether the index falls is >= 0 and index is < string length. If it does then return the index to MyString.*/

char& MyString::operator[](int index) {

assert(index >= 0 && index < strlen(desc));

return desc[index];

}

/* Overloaded Extraction >> operator function takes address of source. A limit of 127 on the number of characters this function will read.We temporarily read into a non-dynamic array and then copy it into your data member, which will be a dynamic array. */

istream& operator>>(istream& in, MyString &source)

{

char temp[127];

delete[] source.desc;

in >> temp;

source.desc = new char[strlen(temp) + 1];

strcpy(source.desc, temp);

return in;

}

/* The read() function returns void and takes two arguments, a stream and the delimiting character. It does not skip leading spaces. The limit of 127 characters imposed on the >> function above also applies to this function. The function :-reads character by character in a loop. Use the in.getline() function to do the reading of the input into a non-dynamic array, then use strcpy() to copy it into your data member.

*/

void MyString::read(istream &source, char delim)

{

char temp[127];

delete[] desc;

source.getline(temp, 127, delim);

desc = new char[strlen(temp) + 1];

strcpy(desc, temp);

}

/*Overloaded operator + function, takes two parameter which is reference to MyString 'left' & 'right' and is declared const. Overload the + operator does MyString concatenation. The operator able to handle either MyString objects or C-strings on either side of the operator. The memory is allocated to hold the new MyString. strcpy() gets the left operand into the result MyString, and then strcat() to append the right operand. Both strcpy() and strcat() is used as if they are void, even though they do have return values.

*/

const MyString operator+(const MyString &left, const MyString &right)

{

MyString temp;

temp = new char[strlen(left.desc) + strlen(right.desc) + 1];

strcpy(temp.desc, left.desc);

strcat(temp.desc, right.desc);

return temp;

}

/* Overloaded the shorthand += to combine concatenation and assignment. The argument to overloaded += operator is reference

to right MyString object. Dynamic allocate memory to hold size of the new MyString and strcat() to append the right operand.

*/

MyString MyString::operator+=(const MyString& right)

{

MyString temp;

temp = new char[strlen(right.desc) + 1];

delete[] desc;

desc = new char[strlen(temp.desc) + strlen(right.desc) + 1];

strcat(desc, right.desc);

return *this;

}

/* Overloaded the shorthand += to combine concatenation and assignment. The argument to overloaded += operator is pointer

to right char object. Dynamic allocate memory to hold the size of the new MyString and strcat() to append the right operand.

*/

MyString MyString::operator+=(const char *right)

{

MyString temp;

temp = new char[strlen(right) + 1];

delete[] desc;

desc = new char[strlen(temp.desc) + strlen(right) + 1];

strcat(desc, right);

return *this;

}

}