advanced9-23.cpp

//The purpose of this assignment was to create a program that would
//allow teachers to input three test scores, and get the average of
//those three. It specifically required the use of two functions
//(getTestScore and calcAverage)in the way I use them below. I 
//added functionality to make it so that if the teacher put in a 
//wrong value, such as a letter in place of a number for a number 
//only variable (double or int) it would simply ask for input again
//until such a time as valid input is given. Also ensured that the
// >> operator would not freeze with invalid input. I also enabled
//teachers to do this for a certain number of students, and assign 
//an "ID" string to each result for convenience. We haven't gotten
//to arrays in the book yet, but it would have been great to use 
//an array to store/display the data. Also made it so that a 
//negative number entered into a test score would act as a sentinel
//value for the entire program. I know there must be a more 
//efficient way to do this, but I haven't gotten that far yet.

//Also note that I follow the whitespace convention of indenting
//loops and if statements in entirety, and again for the body.

//Edit: This version includes some alterations made after reading
//the chapter about void functions and passing variables by
//reference.

#include <iostream>
#include <iomanip>
//#include <typeinfo>
//#include <cmath>
//#include <string>

using namespace std;

double getTestScore (double scorePrev, int &sVal, int &tck);
double calcAverage (double scoreA, double scoreB, double scoreC, int track);
void noFail ();

int main()
{
	int sent = 0;

		while (sent == 0)
		{
			cout << endl << "Enter the number of grade sets you would like the average of (any negative integer to end): ";
			cin >> sent; //define sentinel value for while
			noFail();
		}//end while

		while (sent > 0)
		{

			string stuName = " ";
			cout << endl << "Enter student ID: ";
			getline (cin,stuName); //prompt for student name to tag average score/w

			int tick = 1;	//Establish ticker var to send to functions
                    			//Reset ticker on concurrent runs of while loop
			double score3 = 0.0;
			double score2 = 0.0;
			double score1 = getTestScore(0, sent, tick);

			score2 = getTestScore(score1, sent, tick);

			score3 = getTestScore(score2, sent, tick);

				if (tick < 4)//ends while loop without displaying a negative average
				{
					break;
				}//end if
			
			double avg = calcAverage (score1, score2, score3, tick); //Use calcAverage to assign average to avg
			cout << "                    Average score for " << stuName << ": " << fixed << setprecision(1) << avg << endl;
			sent -= 1;

				while (sent == 0)//chance to edit sentine value
				{
					cout << endl << "Enter the number of grade sets you would like the average of (any negative integer to end): ";
					cin >> sent; //define sentinel value for while
					noFail();
				}//end while
		} //end while
	return 0;
}

double getTestScore (double scorePrev, int &sValue, int &tck)
{
	if (scorePrev < 0)
	{
		sValue = -1;
		return -1;
	}//end if
	double score = 0.0;
	while(score > -0.0001 && score < 0.0001)
	{
	    cout << endl << "Enter score #" << tck << ": ";
	    cin >> score;
            noFail();
	}//end while
	tck += 1;
	return score;
}

double calcAverage (double scoreA, double scoreB, double scoreC, int track)
{
	return (scoreA+scoreB+scoreC)/(track-1);
}


void noFail ()
{
	std::cin.clear();
	std::cin.ignore(65536,'\n');
}