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  1. //Maxwell Brewer            CS1A           Chapter 4, P. 225, #21
  2. //
  3. /***************************************************************
  4.  * 
  5.  * CALCULATE AREA OF CIRCLE, RECTANGLE, TRIANGLE
  6.  * ________________________________________________
  7.  * 
  8.  * This program will take user inout of a selection
  9.  * to calculate either the area of a circle, rectandgle,
  10.  * or triangle, then the user will input the measurements.
  11.  * _____________________________________________
  12.  * INPUT
  13.  * 
  14.  * user choice
  15.  * length, width
  16.  * base, height
  17.  * length, height
  18.  * 
  19.  * OUTPUT
  20.  * 
  21.  * User menu
  22.  * Circle sqare units
  23.  * Rectangle sqare units
  24.  * Triangle sqare units
  25.  * 
  26.  ***************************************************************/
  27.  
  28. #include <iostream>
  29. #include <iomanip>
  30. #include <string>
  31. #include <cmath>
  32.  
  33. using namespace std;
  34.  
  35. int main() {
  36.  
  37.   // Initialization
  38.   const char MSG_1[] = "Geometry Calculator";
  39.   const char SEL_1[] = "    1. Calculate the Area of a Circle";
  40.   const char SEL_2[] = "    2. Calculate the Area of a Rectangle";
  41.   const char SEL_3[] = "    3. Calculate the Area of a Triangle";
  42.   const char SEL_4[] = "    4. Quit";
  43.   const char ENT_1[] = "    Enter your choice (1-4):";
  44.  
  45.   int choice; //declare a variable to store user choice.
  46.               //Other init. will come later
  47.  
  48.   //Menu
  49.   cout << MSG_1 << endl;
  50.   cout << SEL_1 << endl;
  51.   cout << SEL_2 << endl;
  52.   cout << SEL_3 << endl;
  53.   cout << SEL_4 << endl
  54.                 << endl;
  55.   cout << ENT_1 << endl;
  56.  
  57.   // Display input prompts
  58.   cin >> choice;
  59.  
  60.   bool valid;               //declare a boolean variable to validate input
  61.  
  62.   cout << setprecision(4) << fixed << showpoint;
  63.  
  64.   // Output
  65.   if(choice == 1){
  66.         const double PI = 3.14159; //declare and initialize pi
  67.         double radius; //declare variable to store radius
  68.  
  69.         cout << "Enter radius: " << endl; //prompt to enter radius
  70.         cin >> radius; //read radius from keyboard as user input
  71.         valid = (radius > 0); //valid will be true if input is positive number
  72.  
  73.         if(valid){ //execute this only if input is valid
  74.             //calculate and print area
  75.             cout << "The area of the Circle is: ";
  76.             cout << (pow(radius, 2) * PI) << " sq. units." <<endl;
  77.         }
  78.         else{ //execute this if input is invalid
  79.             cout << "Invalid input!" << endl;
  80.         }
  81.     }
  82.     else if(choice == 2){
  83.         //declare variables to store length and width
  84.         double length;
  85.         double width;
  86.  
  87.         //prompt to enter length and width
  88.         cout << "Enter length and width: " << endl;
  89.  
  90.         //read them from keyboard
  91.         cin >> length >> width;
  92.  
  93.         //boolean variable valid will be true if
  94.         //both length and width are positive
  95.         valid = (length > 0) && (width > 0);
  96.  
  97.         if(valid){                        //execute only if input is valid
  98.                                           //calculate and print area
  99.             cout << "The area of the Rectangle is: ";
  100.             cout << (length * width) << " sq. units." << endl;
  101.         }
  102.         else{ //execute this if input is invalid
  103.             cout << "Invalid input!" << endl;
  104.         }
  105.     }
  106.     else if(choice == 3){
  107.         //declare variables to store base and height
  108.         double base;
  109.         double height;
  110.  
  111.         //prompt to enter base and height
  112.         cout << "Enter base and height: " << endl;
  113.  
  114.         //read them from keyboard
  115.         cin >> base >> height;
  116.  
  117.         //boolean variable valid will be true if
  118.         //both base and height are positive
  119.         valid = (base > 0) && (height > 0);
  120.  
  121.         if(valid){ //execute only if input is valid
  122.             //calculate and display area
  123.             cout << "The area of the Triangle is: ";
  124.             cout << base * height/2 << " sq. units." << endl;
  125.         }
  126.         else{ //execute this if input is invalid
  127.             cout << "Invalid input!" << endl;
  128.         }
  129.     }
  130.     else if(choice >= 5){
  131.         cout << "ERROR: Choice out of range!" << endl;
  132.     }
  133.  
  134.  
  135. 	return 0;
  136. }
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Geometry Calculator
    1. Calculate the Area of a Circle
    2. Calculate the Area of a Rectangle
    3. Calculate the Area of a Triangle
    4. Quit

    Enter your choice (1-4):
Enter base and height: 
The area of the Rectangle is: 4.0000 sq. units.
https://ideone.com/5VCGOU
Chapter 4, P. 225, #21
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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