Simple class example of c++ for beginners

This class maintain a library card catalog entry.Have the class store a book's title,author,and the number  of copies available.

#include<iostream>
using namespace std;
class card
{
    private:
            char booksTitle[50],author[50];
            int av_copies;
    public:
        set_a()
        {
            cout<<"Enter the Books Title:" << endl;
            cin>> booksTitle;
            cout<<"Author:" << endl;
            cin>> author;
            cout<<"Available copies:" << endl;
            cin>> av_copies;
        }
        show()
        {
            cout<<"Book title:" << booksTitle <<endl;
            cout<<"Authors name:" << author <<endl;
            cout<<"Available copies:" << av_copies <<endl;
        }

};
int main()
  {
      card a;
      a.set_a();
      a.show();
  }

output:

Average marks of a student.

#include<iostream>

using namespace std;

class student

{

    private :

        int x,y,z,avg;

    public:

        void get_avg_marks(int x,int y,int z)

        {

        avg=(x+y+z)/3;

        cout<<avg;

        }

};

int main()

{

    student ab;

    int x,y,z;

    cin>>x>>y>>z;

    ab.get_avg_marks(x,y,z);

    return 0;

}

output:

A simple class of draw line.

#include<iostream>

using namespace std;

class line

{

    private :

        int len;

    public:

        void set_len()

        {

            cin>>len;

        }

        void drawLine()

        {

            cout<<"*";

        }

       int get_len()

        {

            return(len);

        }

};

int main()

{

    line ab;

    int n,i;

     ab.set_len();

    n=ab.get_len();

    for(i=0;i<n;i++)

    {

        ab.drawLine();

    }

}

output:

Rectangle class which has two private data:width and length,

#include<iostream>

using namespace std;

class rectangle

{

    private :int width,length;

    public:

        void get_width()

        {

            cout<<"input width:";

            cin>>width;

        }

        void get_length()

        {

            cout<<"input length:";

            cin>>length;

        }

         void area()

        {

            cout<<"Area is="<<(width*length)<<endl;

        }

};

int main()

{ rectangle rectangle1,rectangle2;

rectangle1.get_width();

rectangle1.get_length();

rectangle1.area();

rectangle2.get_width();

rectangle2.get_length();

rectangle2.area();

return 0;

}

output: