C++ Lab

/*
##This is a program for calculating "Area" of Circle, Square, Rectangle and Triangle.
##This program uses:
    #Condition
    #Loop
    #Array
    #Inheritance
    #Polymorphism
    #Exception
*/

#include <iostream>
#include <cstdlib> //Use for "Press any key to continue..."

using namespace std;

//Super Class
class AreaCalculation{
protected:
    float base, height, width, total_area;
public:
    AreaCalculation(float base){
        this->base = base;
    }
    AreaCalculation(float high, float wide){
        height=high;
        width=wide;
    }
    virtual void calculation(){
    cout<<"Calculation going on"<<endl;
    }
};

//Sub Classes
class Circle: public AreaCalculation{
public:
    Circle(float base):AreaCalculation(base){}
    void calculation()
    {
        total_area= 3.1416*base*base;
        cout<<"Area of the circle is: "<<total_area<<"square meter<s>"<<endl;
    }
};

class Rectangle : public AreaCalculation{
public:
    Rectangle(float high, float wide): AreaCalculation(high, wide){}
    void calculation()
    {
        total_area = height*width;
        cout<<"Area of the rectangle is: "<<total_area<<"square meter<s>"<<endl;
    }
};

class Triangle : public AreaCalculation{
public:
    Triangle(float high, float wide): AreaCalculation(high,wide){}
    void calculation()
    {
        total_area = 0.5*height*width;
        cout<<"Area of triangle is: "<<total_area<<"square meter<s>"<<endl;
    }
};

class Square: public AreaCalculation{
public:
    Square(float base): AreaCalculation(base){}
    void calculation()
    {
        total_area = base*base;
        cout<<"Area of the square is: "<<total_area<<"square meter<s>"<<endl;
    }
};

int main()
{

        //For restarting the program if user wants.
        char in;
        do{
        int opt;
        cout<< "\n\n================================================================="<<endl;
        cout<< "        Find the Areas of Different Geometrical Figures"<<endl;
        cout<< "        ========= Select Your Desired Option =========="<<endl;
        cout<< "================================================================="<<endl;


        cout<<"\n\n1. Area of Circle\n2. Area of Rectangle\n3. Area of Triangle\n4. Area of Square\nChoose your number :  ";
        cin>>opt;
        cout<<"" <<endl;
        AreaCalculation *ac;//object of super class
        int no;
        float hi, wi;
        try
        {
                if(opt == 1){
                try{ //If there is any problem found
                cout<<"How many circle<s>: ";
                cin>>no;
                cout<<"" <<endl;
                float ba[no];
                for(int i=0; i<no; i++)//including array for more than 1 conversion
                {
                    cout<<"Enter the radius of circle "<<i+1<<" :";
                    cin>>ba[i];
                }

                for(int i=0; i<no; i++)
                {
                    if(ba>0)
                    {
                        Circle c1(ba[i]);//object of sub class
                        ac = &c1; // referencing object of sub class to super class
                        ac->calculation();
                    }
                else
                {
                    throw "Radius can not be less than or equal to 0(zero).";
                }

                }

                }catch(const char *msg){
                    cout<<"A problem occurred. "<<msg<<endl;
                }
                }
                else if(opt == 2){
                try{
                cout<<"How many rectangle<s>: ";
                cin>>no;
                float hi[no], wi[no];
                for(int i=0; i<no;i++)
                {
                    cout<<"Enter the length of the rectangle "<<i+1<<" : ";
                    cin>>hi[i];
                    cout<<"Enter the width of the rectangle "<<i+1<<" : ";
                    cin>>wi[i];
                }

                for(int i=0; i<no;i++)
                {
                    if(hi>0 && wi>0)
                    {
                        Rectangle rec(hi[i],wi[i]);
                        ac = &rec;
                        ac->calculation();
                    }
                    else
                    {
                        throw "Length and width can not be less than or equal to 0(zero).";
                    }
                }

                }catch(const char *msg){
                cout<<"A problem occurred. "<<msg<<endl;
                }
                }
                else if(opt == 3)
                {
                try
                {
                cout<<"Enter the height of the triangle: ";
                cin>>hi;
                cout<<"Enter the base of the triangle: ";
                cin>>wi;
                if(hi>0)
                {
                    try
                    {
                        if(wi>0)
                        {

                            Triangle tri(hi,wi);
                            ac = &tri;
                            ac->calculation();
                        }
                        else{
                            throw "Base cannot be less than or equal to 0(zero).";
                        }


                }catch (const char *msg){
                        cout<<"\nA problem occurred. "<<msg<<endl;
                    }
                }
                else
                {
                throw "Height can not be less than or equal to 0(zero).";
                }
                }catch(const char *msg){
                    cout<<"\nA problem occurred. "<<msg<<endl;
                }
                }
                else if(opt == 4){
                try{
                cout<<"Enter how many square<s>: ";
                cin>>no;
                float ba[no];
                for(int i=0; i<no; i++)//including array for more than 1 conversion
                {
                    cout<<"Enter the base of square no. "<<i+1<<" :";
                    cin>>ba[i];
                }

                for(int i=0; i<no; i++)
                {
                    if(ba>0)
                    {
                        Square sq(ba[i]);
                        ac = &sq; // referencing object of sub class to super class
                        ac->calculation();
                    }
                else
                {
                    throw "Base can not be less than or equal to 0(zero).";
                }

                }

                }catch(const char *msg){
                    cout<<"A problem occurred. "<<msg<<endl;
                }
                }
            else{
                throw "Invalid Option. Please try again.";
                }
            }catch(const char *msg)
            {
                cout<<msg<<endl<<"Thank you.\n"<<endl;
            }

            system("PAUSE");



            cout<<"Do you want to convert any other geometric figure?(Y/N): ";
            cin>>in;

        }while(in=='y'||in=='Y');
    }