You are given two files mystring1.h the document and mystring1.cpp the document which define a String class implemented by using static array as the data member. The purpose of this assignment is to rewrite this class by replacing the static array with a pointer (dynamic array). You are required to modify the String class accordingly:

Data: we wish to allow our String class to accommodate strings of different sizes. To that end, instead of storing a strings characters in a fixed-size array, each String object should contain the following data as part of its internal representation:

(1) a character pointer meant to point to a dynamically-allocated array of characters.

(2) a length field that will hold the current length of the string at any given moment.

Operations: same as the methods in String class, plus the big three( destructor, copy constructor, and assignment operator overloading).

Modularity: The String class code must be put in its own module, i.e., a file mystring2.h (the header file) should hold the class definition (use conditional compilation directives) and a file mystring2.cpp (the implementation file) should hold the method definitions.

************************************************************************************************************

For this program we have to file the code in the template header file and main file.

*************************************************************************************************************

//File: mystring1.h

// ================

// Interface file for user-defined String class.

#include"mystring1.h

String::String()

{

contents[0] = '\0';

len = 0;

}

String::String(const char s[])

{

len = strlen(s);

strcpy(contents, s);

}

void String::append(const String &str)

{

strcat(contents, str.contents);

len += str.len;

}

bool String::operator ==(const String &str) const

{

return strcmp(contents, str.contents) == 0;

}

bool String::operator !=(const String &str) const

{

return strcmp(contents, str.contents) != 0;

}

bool String::operator >(const String &str) const

{

return strcmp(contents, str.contents) > 0;

}

bool String::operator <(const String &str) const

{

return strcmp(contents, str.contents) < 0;

}

bool String::operator >=(const String &str) const

{

return strcmp(contents, str.contents) >= 0;

}

String String::operator +=(const String &str)

{

append(str);

return *this;

}

void String::print(ostream &out) const

{

out << contents;

}

int String::length() const

{

return len;

}

char String::operator [](int i) const

{

if (i < 0 || i >= len) {

cerr << "can't access location " << i

<< " of string \"" << contents << "\"" << endl;

return '\0';

}

return contents[i];

}

ostream & operator<<(ostream &out, const String & s) // overload ostream operator "<<" - External!

{

s.print(out);

return out;

}

*************************************************************************************************************

//File: mystring1.h

// ================

// Interface file for user-defined String class.

#ifndef _MYSTRING_H

#define _MYSTRING_H

#include

#include // for strlen(), etc.

using namespace std;

#define MAX_STR_LENGTH 200

class String {

public:

String();

String(const char s[]); // a conversion constructor

void append(const String &str);

// Relational operators

bool operator ==(const String &str) const;

bool operator !=(const String &str) const;

bool operator >(const String &str) const;

bool operator <(const String &str) const;

bool operator >=(const String &str) const;

String operator +=(const String &str);

void print(ostream &out) const;

int length() const;

char operator [](int i) const; // subscript operator

private:

char contents[MAX_STR_LENGTH+1];

int len;

};

ostream & operator<<(ostream &out, const String & r); // overload ostream operator "<<" - External!

#endif /* not defined _MYSTRING_H */

*************************************************************************************************************

/**

* cmpsc122 Assignment test file

* File Name: mystringDriver.cpp

*

* Description: This program demonstrates a basic String class that implements

* dynamic allocation and operator overloading.

*

*/

#include

#include "mystring2.h

using namespace std;

/************************ Function Prototypes ************************/

/*

* Function: PrintString

* Usage: PrintString(str);

*

* Prints out the value and length of the String object passed to it.

*/

void PrintString(const char *label,

const String &str); // overloaded ostream operator << is used in the definition.

/*************************** Main Program **************************/

int main()

{

String str1, str2("init2"), str3 = "init3"; // Some String objects. Using constructor for copy

char s1[100], s2[100], s3[100]; // Some character strings.

// Print out their initial values...

cout << "Initial values:" << endl;

PrintString("str1", str1);

PrintString("str2", str2);

PrintString("str3", str3);

// Store some values in them...

cout << " Enter a value for str1 (no spaces): ";

cin >> s1;

str1 = s1;

cout << " Enter a value for str2 (no spaces): ";

cin >> s2;

str2 = s2;

cout << " Enter a value for str3 (no spaces): ";

cin >> s3;

str3 = s3;

cout << " After assignments..." << endl;

PrintString("str1", str1);

PrintString("str2", str2);

PrintString("str3", str3);

// Access some elements...

int i;

cout << " Enter which element of str1 to display: ";

cin >> i;

cout << "Element #" << i << " of str1 is '" << str1[i]

<< "'" << endl;

cout << " Enter which element of str2 to display: ";

cin >> i;

cout << "Element #" << i << " of str2 is '" << str2[i]

<< "'" << endl;

cout << " Enter which element of str3 to display: ";

cin >> i;

cout << "Element #" << i << " of str3 is '" << str3[i]

<< "'" << endl;

// Append some strings...

cout << " Enter a value to append to str1 (no spaces): ";

cin >> s1;

// str1.append(s1); // Actually, the cstring is converted to String object here by the constructor

str1 += s1; // same as above

cout << " Enter a value to append to str2 (no spaces): ";

cin >> s2;

str2 += s2;

cout << " Enter a value to append to str3 (no spaces): ";

cin >> s3;

str3 += s3;

cout << " After appending..." << endl;

PrintString("str1", str1);

PrintString("str2", str2);

PrintString("str3", str3);

// Compare some strings...

cout << " Comparing str1 and str2..." << endl;

cout << "\"";

cout<< str1; // test the overloading of ostream operator <<

cout << "\" is ";

if (str1 < str2) { // test the overloading of comparison operator <

cout << "less than";

} else if (str1 > str2) {

cout << "greater than";

} else {

cout << "equal to";

}

cout << " \"";

cout << str2;

cout << "\"" << endl;

cout << " test the = operator, after str1 = str2; "<< endl;

str1 = str2;

PrintString("str1", str1);

PrintString("str2", str2);

str1 += s1;

cout << " After str1 = str1 + s1: "<< endl;

PrintString("str1", str1);

PrintString("str2", str2);

String str4(str3);

cout << " test the copy constructor, after str4(str3);"<< endl;

PrintString("str3", str3);

PrintString("str4", str4);

cout << " after appending str3 by str2" << endl;

str3 += str2;

PrintString("str3", str3);

PrintString("str4", str4);

cout<< " str2, str4 are not changed. Type any letter to quit." << endl;

char q;

cin >> q;

return 0;

}

/*********************** Function Definitions **********************/

void PrintString(const char *label,

const String &str)

{

cout << label << " holds \"";

cout << str; // << is overloaded

cout << "\" (length = " << str.length() << ")" << endl;

}