//Program implementing a string class and all the related
//operations...

#include "iostream.h"
#include "conio.h"
#include "stdlib.h"


class strings //Class definition
{
    char *string; //for the string data

    public:
        int len;      //for lenght of string

        strings() //Default constructor
        {*string = NULL;len = 0;}

        strings(char *a) //Parameterized constructor
        {
            len = str_len(a);
            /*while (*a)
                len++;*/
            //*a -= len;
            string = new char[len+1];
            while (*a)
            {
                *string = *a;
                string++;
                a++;
            }
            *string = '\0';
            string -= len;
        }

//        ~strings() //Destructor freeing memory
//        {delete []string;}

        void getdata() //When the entry is going to be taken from user
        {
            delete [] string;
            char *a;
            cout << endl << endl <<"Enter the string to be operated upon (Maxlength = 100): ";
            cin.getline (a,100);
            len = str_len(a);
            //while (*a)
              //    len++;
            //a -= len;
            string = new char[len+1];
            while (*a)
            {
                *string = *a;
                string ++;
                a++;
            }
            *string = '\0';
            string -= len;
        }
        void displaydata() //Displaying data to the user
        {
            cout << endl << endl << "Your string is : " << string;
        }

        //Function Declarations which will operate on the string
        void strcpy(strings &);
};

void strings::strcpy (strings &source)
{
    delete []string;
    string = new char[source.len+1];

    while (*source.string)
    {
        *string = *source.string;
        string ++;
        source.string++;
    }
    *string = '\0';
    string -= len;
}

int str_len (const char *a)
{
    int len = 0;
    while (*a)
    {
        len++;
        a++;
    }
    return len;
}

void main()
{
    clrscr();
    char *str;
    int choice;
    strings main_string;

    //Taking entry for the main string
    main_string.getdata();

    clrscr();

do
{
    clrscr();
    //Providing menu
    cout << "\t\tMenu for the operations on the given string" << endl
        << "1. Change the Main String." << endl
        << "2. Display the string." << endl
        << "3. Count the length of the string." << endl
        << "4. Copy a string into the main string." << endl
        << "0. Exit" << endl;

    //Taking choice
    cout << endl << "Enter the no. of your choice here : ";
    cin >> choice;
    cin.ignore();

    //Taking actions
    switch (choice)
    {
        case 1:
            main_string.getdata();
        break;
        case 2:
            main_string.displaydata();
            cin.get();
        break;
        case 3:
            cout << endl << "Length of the string = " << main_string.len;
            cin.get();
        break;
        case 4:
            cout << endl <<"Enter a string to be copied (Maxlength = 100) : ";
            cin.getline(str,100);
            strings temp_string (str);
            temp_string.displaydata();
            cin.get();
            main_string.strcpy(temp_string);
        break;
        case 0:
            cout << endl << "\t\t\t\tThank You";
            cin.get();
            exit(0);
        break;
        default :
            cout << endl << "\t\t\t\tWrong Entry";
            cin.get();
        break;
    }
    getch();
} while (choice != 0);

}