cout << "Choose the material of the rodnn";
cout << "S For STEELnA For ALUMINUMnC For COPPERnT For TITANIUMnn";
cin >> meterial;

switch (meterial)

{
case 's':
    cout << "nEnter the diameter of the rod in mm: ";
    cin >> diameter;
    area = (pi * diameter * diameter) / 4;


    while (i <= 100)

        stress = F / area;
        strain = 200 / stress;
        F = F + 100;


        cout <<"Load = " << F << "  Stress = " << stress << " N/mm^2" << "  Strain = " << strain << "n";
        i++;



        break;
case 'a':
            cout << "Enter the diameter of the rod in mm: ";
            cin >> diameter;
            area = (pi * diameter * diameter) / 4;


            while (i <= 100)

                stress = F / area;
                strain = 69 / stress;
                F = F + 100;


                cout << "Load = " << F << "  Stress = " << stress << " N/mm^2" << "  Strain = " << strain << "n";
                i++;


                break;
case 'c':
    cout << "Enter the diameter of the rod in mm: ";
    cin >> diameter;
    area = (pi * diameter * diameter) / 4;


    while (i <= 100)

        stress = F / area;
        strain = 117 / stress;
        F = F + 100;


        cout << "Load = " << F << "  Stress = " << stress << " N/mm^2" << "  Strain = " << strain << "n";
        i++;


        break;
case 't':
    cout << "Enter the diameter of the rod in mm: ";
    cin >> diameter;
    area = (pi * diameter * diameter) / 4;


    while (i <= 100)

        stress = F / area;
        strain = 110.3 / stress;
        F = F + 100;


        cout << "Load = " << F << "  Stress = " << stress << " N/mm^2" << "  Strain = " << strain << "n";
        i++;

        break;
default:
    cout << "You entered a wrong character";



    }
}