Chapter-2/2-20.cpp

   1 /* C++ How to Program, 9/E, by Paul Deitel & Harvey Deitel.
   2
   3 Solution of exercise 2.20:
   4 (Diameter, Circumference and Area of a Circle) Write a program that reads in
   5 the radius of a circle as an integer and prints the circle's diameter,
   6 circumference and area. Use the constant value 3.14159 for π. Do all
   7 calculations in output statements. [Note: In this chapter, we’ve discussed
   8 only integer constants and variables. In Chapter 4 we discuss floating-point
   9 numbers, i.e., values that can have decimal points.]
  10
  11 Written by Juan Carlos Moreno (jcmhsoftware@gmail.com), 2022/01/02 */
  12
  13 #include <iostream>
  14
  15 using namespace std;
  16
  17 int main()
  18 {
  19         int radius;
  20
  21         cout << "Enter radius of the circle: ";
  22         cin >> radius;
  23
  24         cout << "Diameter of the circle is " << 2*radius << endl; //D = 2r
  25         cout << "Circumference of the circle is " << 2*3.14159*radius //C = 2πr
  26              << endl;
  27         cout << "Area of the circle is " << 3.14159*radius*radius //A = πr^2
  28              << endl;
  29
  30         return 0;
  31 }