Function 2

#include <iostream>
#include <cmath>
#include <string>
using namespace std;

void square(float, float &, float &);
void Cicle(float , float &, float &);
void rectangle(float, float, float &, float &);
void parallelogram(float, float, float, float &, float &);
void triangle(float, float, float, float, float &, float &);
void trapezoid(float, float, float, float, float, float &, float &);

int main()
{
    int option;
    char askExit;
    string shape;
    float a, b, c, d, r, h, alpha, area, perimeter;

    do
    {
        system("cls");
        cout << "Calculate area of:\n";
        cout << "\t1 - Square\n\t2 - Circle\n\t3 - Rectangle\n\t4 - Parallelogram\n\t5 - Triangle\n\t6 - Trapezoid";

        cout << "\nYour selection: ";
        cin >> option;

        if (option==1)
        {
            shape = "square";
            cout << "a: ";
            cin >> a;

            square(a, area, perimeter);
        }

        else if (option==2)
        {
            shape = "circle";
            cout << "radius: ";
            cin >> r;

            Cicle(r, area, perimeter);
        }

        else if (option==3)
        {
            shape = "rectangle";
            cout << "a: ";
            cin >> a;
            cout << "b: ";
            cin >> b;

            rectangle(a, b, area, perimeter);
        }

        else if (option==4)
        {
            shape = "parallelogram";
            cout << "a: ";
            cin >> a;
            cout << "b: ";
            cin >> b;
            cout << "alpha (rad): ";
            cin >> alpha;

            parallelogram(a, b, alpha, area, perimeter);
        }

        else if (option==5)
        {
            shape = "triangle";
            cout << "a: ";
            cin >> a;
            cout << "b: ";
            cin >> b;
            cout << "c: ";
            cin >> c;
            cout << "h: ";
            cin >> h;

            triangle(a, b, c, h, area, perimeter);
        }

        else
        {
            shape = "trapezoid";
            cout << "a: ";
            cin >> a;
            cout << "b: ";
            cin >> b;
            cout << "c: ";
            cin >> c;
            cout << "d: ";
            cin >> d;
            cout << "h: ";
            cin >> h;

            trapezoid(a, b, c, d, h, area, perimeter);
        }

        cout << "Area of " << shape << " is " << area << " and perimeter is " << perimeter;

        cout << "\nRepeat the whole process? (Y/N): ";
        cin >> askExit;

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

}

void square(float a, float &area, float &perimeter)
{
    area = a*a;
    perimeter = 4*a;
}

void Cicle(float r, float &area, float &perimeter)
{
    area = 3.14159*r*r;
    perimeter = 2*3.14159*r;
}

void rectangle(float a, float b, float &area, float &perimeter)
{
    area = a*b;
    perimeter = (2*a)+(2*b);
}

void parallelogram(float a, float b, float alpha, float &area, float &perimeter)
{
    area = a*b*sin(alpha);
    perimeter = 2*(a+b);
}

void triangle(float a, float b, float c, float h, float &area, float &perimeter)
{
    area = a*h/2;
    perimeter = a+b+c;
}

void trapezoid(float a, float b, float c, float d, float h, float &area, float &perimeter)
{
    area = (a+b)*h/2;
    perimeter = a+b+c+d;
}