Chapter-4/4-13.cpp

   1 /*C++ How to Program, 9/E, by Paul Deitel & Harvey Deitel.
   2
   3 Solution of exercise 4.13:
   4 (Gas Mileage) Drivers are concerned with the mileage obtained by their
   5 automobiles. One driver has kept track of several trips by recording miles
   6 driven and gallons used for each trip. Develop a C++ program that uses a while
   7 statement to input the miles driven and gallons used for each trip. The
   8 program should calculate and display the miles per gallon obtained for each
   9 trip and print the combined miles per gallon obtained for all tankfuls up to
  10 this point.
  11
  12     Enter miles driven (-1 to quit): 287
  13     Enter gallons used: 13
  14     MPG this trip: 22.076923
  15     Total MPG: 22.076923
  16
  17     Enter miles driven (-1 to quit): 200
  18     Enter gallons used: 10
  19     MPG this trip: 20.000000
  20     Total MPG: 21.173913
  21
  22     Enter the miles driven (-1 to quit): 120
  23     Enter gallons used: 5
  24     MPG this trip: 24.000000
  25     Total MPG: 21.678571
  26
  27     Enter the miles used (-1 to quit): -1
  28
  29 Written by Juan Carlos Moreno (jcmhsoftware@gmail.com), 2023-01-16.*/
  30
  31 #include <iostream>
  32 #include <iomanip>
  33
  34 using namespace std;
  35
  36 int main()
  37 {
  38     double miles; //Miles driven for each trip
  39     double gallons; //Gallons used for each trip
  40     double total_miles = 0; //Miles driven for all trips
  41     double total_gallons = 0; //Gallons used for all trips
  42
  43     while (miles != -1)
  44     {
  45         cout << "Enter miles driven (-1 to quit): ";
  46         cin >> miles;
  47
  48         if (miles != -1)
  49         {
  50             cout << "Enter gallons used: ";
  51             cin >> gallons;
  52             total_gallons += gallons;
  53             total_miles += miles;
  54             cout << setprecision(6) << fixed;
  55             cout << "MPG this trip: " << miles/gallons << endl;
  56             cout << "Total MPG: " << total_miles/total_gallons
  57                  << endl << endl;
  58         }
  59     }
  60
  61     return 0;
  62 }