/*
   lab04.cpp
   CIS 150
   6/2/2005
   David Klick
   
   This program demonstrates the use of selection structures
   in C++.
*/

#include <iostream>
#include <iomanip>
using std::cin;
using std::cout;
using std::setprecision;
using std::fixed;
using std::showpoint;

int main(void) {
   const double PI = 3.1415926536;
   char choice;          // user's menu choice
   bool valid = true;    // whether user input was valid
   bool quit = false;    // whether user chose to quit program
   double radius;        // for circle
   double length, width; // for rectangle
   double base, height;  // for triangle
   double area;          // for results of all calcs
   
   // display menu
   cout << "Area calculator\n\n"
        << "1. (C)ircle\n\n"
        << "2. (R)ectangle\n\n"
        << "3. (T)riangle\n\n"
        << "4. E(x)it\n\n"
        << "Choice: ";
   cin >> choice;
   
   // menu choice processing
   switch (choice) {
   case '1':
   case 'C':
   case 'c':
      cout << "\nEnter radius of circle ( >0 ): ";
      cin >> radius;
      if (radius <= 0.0) {
         cout << "Error: radius out of range\n";
         valid = false;
      } else {
         area = PI * radius * radius;
      }
      break;
   case '2':
   case 'R':
   case 'r':
      cout << "\nEnter length and width of rectangle ( >0 ): ";
      cin >> length >> width;
      if (length <= 0.0) {
         cout << "Error: length out of range\n";
         valid = false;
      }
      if (width <= 0.0) {
         cout << "Error: width out of range\n";
         valid = false;
      }
      if (valid) {
         area = length * width;
      }
      break;
   case '3':
   case 'T':
   case 't':
      cout << "\nEnter base and height of triangle ( >0 ): ";
      cin >> base >> height;
      if (base <= 0.0) {
         cout << "Error: base out of range\n";
         valid = false;
      }
      if (height <= 0.0) {
         cout << "Error: height out of range\n";
         valid = false;
      }
      if (valid) {
         area = 0.5 * base * height;
      }
      break;
   case '4':
   case 'X':
   case 'x':
      cout << "Thank you for using AreaCalc XP\n";
      quit = true;
      break;
   default:
      cout << "Error: invalid menu choice\n";
      valid = false;
   }

   // display area if no errors encountered and
   //    user didn't choose to quit
   if (!quit && valid) {
      cout << "The area is " << fixed << showpoint
           << setprecision(3) << area << '\n';
   }
 
   cout << "Normal program termination\n";       
   return 0;
}