Converts

#include <iostream>

using namespace std;

int main()
{
    cout << "This is a programme about converts in length units." << endl;
    cout << "The units that are used in this programme are: " << endl << endl;
    cout << "Meters (and dm and cm), yards, feet and inches" << endl;
    cout << "There are the following choices: " << endl << endl;
    cout << "1.  Meter ---> Yard" << endl;
    cout << "2.  Meter ---> Feet" << endl;
    cout << "3.  Meter ---> Inch" << endl;
    cout << "4.  Yard ---> Meter" << endl;
    cout << "5.  Yard ---> Feet" << endl;
    cout << "6.  Yard ---> Inch" << endl;
    cout << "7.  Feet ---> Yard" << endl;
    cout << "8.  Feet ---> Feet" << endl;
    cout << "9.  Feet ---> Inch" << endl;
    cout << "10. Inch ---> Meter" << endl;
    cout << "11. Inch ---> Feet" << endl;
    cout << "12. Inch ---> Inch" << endl << endl;

    // Ask from the user which convert to do
    cout << "Press a number from 1 to 12 to choose which convert do you want me to do." << endl;
    int choice;
    cin >> choice;

    double data;

    // The convert is:
    // 1 foot = 0.305 meters
    // 1 foot = 12 inches , so inch = 2.54 cm
    // 1 yard = 3 feet = 36 inches, so yard = 0.915 meters
    switch(choice){

    case 1:

        cout << "How many meters? " << endl << endl;
        cin >> data;
        cout << data << " meters = " << data * 10 << " dm = " << data * 100 << " cm = ";
        cout << 1000 * data << " mm = " << 1 / 0.915 * data << " yards " << endl << endl;

    case 2:

        cout << "How many meters? " << endl << endl;
        cin >> data;
        cout << data << " meters = " << data * 10 << " dm = " << data * 100 << " cm = ";
        cout << 1000 * data << " mm = " << 1 / 0.305 * data << " yards " << endl << endl;

    case 3:

        cout << "How many meters? " << endl << endl;
        cin >> data;
        cout << data << " meters = " << data * 10 << " dm = " << data * 100 << " cm = ";
        cout << 1000 * data << " mm = " << 1 / (0.305 / 12) * data << " yards " << endl << endl;

    case 4:

        cout << "How many yards? " << endl << endl;
        cin >> data;
        cout << data << " yards = " << 0.915 * data << " meters = " << 9.15 * data << " dm = ";
        cout << 91.5 * data << " cm = " << 915 * data << " mm" << endl << endl;

    case 5:

        cout << "How many yards? " << endl << endl;
        cin >> data;
        cout << data << " yards = " << 3 * data << " feet" << endl << endl;


    case 6:

        cout << "How many yards? " << endl << endl;
        cin >> data;
        cout << data << " yards = " << 36 * data << " inches" << endl << endl;

   default:;

    }

    return 0;

}