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Loop Question

CassandraB (14)
This program calculates average miles per gallon. Calculates average gas price and calculates the cost for a car to go one mile. Everything is executing just fine, the only problem I am having is say I enter just 1 beginning - end odometer reading and one gas reading, if I stop the loop there, it still asks for the price paid at gas station 2 and 3. How do I make it to where say the person enters 10 different gas stops, I need to be able to enter 10 different prices, same with just one gas stop.

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

int main()
{
	double startingMiles, endMiles, totalMiles, averageMiles, ppg, totalPPG, countPPG, averagePPG, perMile, gallons, totalGallons;
	startingMiles = 0;
	endMiles = 0;
	totalMiles = 0;
	totalGallons =0.0;
	char more;
	more = 'y';
	while (more == 'y' || more == 'Y') // allow both Y and y answer
	{
		cout << "\n Enter the beginning odometer reading >" ; // Starting Reading
		cin >> startingMiles;
	

		while (startingMiles < endMiles)
		{
			cout << "\n Input error! end odometer reading must be greater than the last reading! "<<endl; // If Start is Greater than End, Output Error
			cout <<"Enter the ending odometer reading > ";
			cin >> endMiles;
		}


		cout << "\n Enter the ending odmeter reading >"; //End Reading
		cin >> endMiles;
		while (endMiles <= startingMiles)
		{
			cout << "\n Input error! end odometer reading must be greater than starting reading! "<<endl; // If Start is Greater than End, Output Error
			cout <<"Enter the ending odometer reading > ";
			cin >> endMiles;
		}
		cout << "\n Enter the gallons required for your fill-up > " ; // Gallons in Fill up
		cin >> gallons;
		totalGallons +=gallons; //accumulate running gallons total

		while (gallons <= 0)
		{
			cout << "\n Input error! Please Re-Enter > ";
			cin >> gallons;
		}
		totalMiles += endMiles - startingMiles; // calculate total miles driven

		cout <<endl;


		cout << "Enter y to enter more readings or n to quit> "; // Does customer have more inputs
		cin >> more;

			if (more != 'Y' && more != 'y' && more != 'N' && more != 'n')  // Validate input allowing only YyNn answers
		{
			cout <<"Invalid entry. Please enter Y or N";
				cin >> more;

		}

	
	}
	cout <<endl; 

	averageMiles = totalMiles / totalGallons; // Calculate the averageMiles

	totalPPG = 0;
	for (countPPG = 0; countPPG < 3; countPPG++)
	{
		cout << "\n Enter the price per gallon at station #" << countPPG + 1 << " $" ;
		cin >> ppg;
		while (ppg <= 0)
		{
			cout << "\n That is not a valid price. Please Enter Again $"<<endl;
			cin >> ppg;
		}
		totalPPG += ppg;
	}
	averagePPG = totalPPG / countPPG; // calculate average miles per gallon
	
	perMile = averagePPG / averageMiles;

	cout <<endl;
	cout << setprecision(1) << fixed;
	cout << "Your cars average miles-per-gallon is> " << averageMiles <<endl;
	cout << setprecision(2) << fixed;
	cout << "You bought gas at an average $" << averagePPG << " per gallon" <<endl;
	cout << "The cost for your car to 1 mile is $" << perMile <<endl;



	if (averageMiles >= 0 && averageMiles <= 15) // determine effeciency of vehicle
	{
		cout << "Your car is Very Inefficient " <<endl;
	}
	else if (averageMiles >= 16 && averageMiles <= 30)
	{
		cout << "Your car is Reasonably Effecient " <<endl;
	}
	else if (averageMiles >= 31)
	{
		cout << "Your car is Very Efficient " <<endl;
	}

	system("pause");
	return(0);
}
chicofeo (640)
Wrong Info.
Last edited on
CassandraB (14)
@chicofeo,

She does not want us asking the number of gas stations, only relying on the input y/n loop. If the user stops after 1 input, the asking for amount paid for gas would only be one time. If the user inputs 3 different fill ups, then the asking amount paid would be 3 times.
MikeyBoy (5631)
Why do you need a separate loop to enter the PPG? Since you want to enter the PPG once each time the user enters 'y', why not simply do it inside that loop?

EDIT: If there's some reason you need a separate loop, then the reason for your problem should be obvious - you've hardcoded that loop to iterate 3 times. You should change it to iterate the same number of times as the user chose to fill up.
Last edited on
chicofeo (640)
There are couple of things about the code i have questions. However, my focus is to help you in the current situation. The code below, I added it some stuff that I marked as /************/ I add it an accumulator to be used depending on the user answer in the y/n input.

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

int main()
{
    double startingMiles, endMiles, totalMiles, averageMiles, ppg, totalPPG, countPPG, averagePPG, perMile, gallons, totalGallons;
    startingMiles = 0;
    endMiles = 0;
    totalMiles = 0;
    totalGallons = 0.0;
    /**********************/
    int numGasStations = 0; // Declare and Initialize the variable accumulator.
    /**********************/
    char more;
    more = 'y';
    while (more == 'y' || more == 'Y') // allow both Y and y answer
    {
	   cout << "\n Enter the beginning odometer reading >"; // Starting Reading
	   cin >> startingMiles;


	   while (startingMiles < endMiles)
	   {
		  cout << "\n Input error! end odometer reading must be greater than the last reading! " << endl; // If Start is Greater than End, Output Error
		  cout << "Enter the ending odometer reading > ";
		  cin >> endMiles;
	   }


	   cout << "\n Enter the ending odmeter reading >"; //End Reading
	   cin >> endMiles;
	   while (endMiles <= startingMiles)
	   {
		  cout << "\n Input error! end odometer reading must be greater than starting reading! " << endl; // If Start is Greater than End, Output Error
		  cout << "Enter the ending odometer reading > ";
		  cin >> endMiles;
	   }
	   cout << "\n Enter the gallons required for your fill-up > "; // Gallons in Fill up
	   cin >> gallons;
	   totalGallons += gallons; //accumulate running gallons total

	   while (gallons <= 0)
	   {
		  cout << "\n Input error! Please Re-Enter > ";
		  cin >> gallons;
	   }
	   totalMiles += endMiles - startingMiles; // calculate total miles driven

	   cout << endl;


	   cout << "Enter y to enter more readings or n to quit> "; // Does customer have more inputs
	   cin >> more;

	   /***********************************/
	   if (more == 'Y' || more == 'y') // If yes, then the accumulator will add 1 gas stop
		  numGasStations++;

	   else if (more == 'N' || more == 'n') // If no, then there will be AT LEAST 1 gas stop.
		  numGasStations = 1;
	   /***********************************/

	   if (more != 'Y' && more != 'y' && more != 'N' && more != 'n')  // Validate input allowing only YyNn answers
	   {
		  cout << "Invalid entry. Please enter Y or N";
		  cin >> more;

	   }


    }
    cout << endl;

    averageMiles = totalMiles / totalGallons; // Calculate the averageMiles

    totalPPG = 0;

     /*************************************/
    // Change it from 3 to numGasStations to loop as many as required, pending the answer from the user
    // To add more data.
    for (countPPG = 0; countPPG < numGasStations; countPPG++) //Run the loop up to the number of gas stations.
    {
	   cout << "\n Enter the price per gallon at station #" << countPPG + 1 << " $";
	   cin >> ppg;
	   while (ppg <= 0)
	   {
		  cout << "\n That is not a valid price. Please Enter Again $" << endl;
		  cin >> ppg;
	   }
	   totalPPG += ppg;
    }
    averagePPG = totalPPG / countPPG; // calculate average miles per gallon

    perMile = averagePPG / averageMiles;

    cout << endl;
    cout << setprecision(1) << fixed;
    cout << "Your cars average miles-per-gallon is> " << averageMiles << endl;
    cout << setprecision(2) << fixed;
    cout << "You bought gas at an average $" << averagePPG << " per gallon" << endl;
    cout << "The cost for your car to 1 mile is $" << perMile << endl;



    if (averageMiles >= 0 && averageMiles <= 15) // determine effeciency of vehicle
    {
	   cout << "Your car is Very Inefficient " << endl;
    }
    else if (averageMiles >= 16 && averageMiles <= 30)
    {
	   cout << "Your car is Reasonably Effecient " << endl;
    }
    else if (averageMiles >= 31)
    {
	   cout << "Your car is Very Efficient " << endl;
    }

    system("pause");
    return(0);
}
AbstractionAnon (6954)
Lines 21-26: Your editing doesn't seem right. Line 18, you're checking the starting mileage. Line 24-25: You ask for the ending miles. If the test at line 21 fails, you will never input the correct starting mileage.

Lines 96-100: What happens if averageMiles is 30.5?
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