Question

You are to implement a MyString class which is our own limited implementation of the std::string

Header file and test (main) file are given in below, code for mystring.cpp.

Here is header file

mystring.h

/* MyString class */

#ifndef MyString_H

#define MyString_H

#include <iostream>

using namespace std;

class MyString {

private:

   char* str;

   int len;

public:

   MyString();

   MyString(const char* s);

   MyString(MyString& s);

   ~MyString();

   friend ostream& operator <<(ostream& os, MyString& s); // Prints string

   MyString& operator=(MyString& s); //Copy assignment

   MyString& operator+(MyString& s); // Creates a new string by concantenating input string

};

#endif

Here is main file, the test file

testMyString.cpp

/* Test for MyString class */

#include <iostream>

#include "mystring.h"

using namespace std;

int main()

{

char greeting[] = "Hello World!";

MyString str1(greeting); // Tests constructor

cout << str1 << endl; // Tests << operator. Should print Hello World!

char bye[] = "Goodbye World!";

MyString str2(bye);

cout << str2 << endl; // Should print Goodbye World!

MyString str3{str2}; // Tests copy constructor

cout << str3 << endl; // Should print Hello World!

str3 = str1; // Tests copy assignment operator

cout << str3 << endl; // Should print Goodbye World!

str3 = str1 + str2; // Tests + operator

cout << str3 << endl; // Should print Hello World!Goodbye World!

return 0;

}

Answer 1

#include "mystring.h"
#include <cstring>

MyString::MyString() {
    str = new char[1];
    str[0] = '\0';
}

MyString::MyString(const char *s) {
    str = new char[strlen(s) + 1];
    strcpy(str, s);
}

MyString::MyString(MyString &s) {
    str = new char[strlen(s.str) + 1];
    strcpy(str, s.str);
}

MyString::~MyString() {
    delete[] str;
}

MyString &MyString::operator=(MyString &s) {
    str = new char[strlen(s.str) + 1];
    strcpy(str, s.str);
    return *this;
}

MyString &MyString::operator+(MyString &s) {
    MyString *result = new MyString();
    result->str = new char[strlen(s.str) + strlen(str) + 1];
    strcpy(result->str, str);
    strcat(result->str, s.str);
    return *result;
}

ostream &operator<<(ostream &os, MyString &s) {
    os << s.str;
    return os;
}