grades.cpp

// Regina Imhoff
// Ecampus CS 161
// Assignment #6
// makes histogram of students' grades as entered by an instructor

#include <iostream> // includes and statements section
#include <string> // strings
#include <cstdlib> //c standard library
#include <stdio.h>
#include <string.h>

using std::cin; // user input
using std::cout; // machine output
using std::endl; // for line breaks 
using std::string; //string
using std::getline; // getline

const int MINIMUM_GRADE = 0;
const int MAXIMUM_GRADE = 5;
const int GRADES = MAXIMUM_GRADE - MINIMUM_GRADE + 1; // Number of grades in the range between minimum and maximum, inclusive.
const int STOP = -1;
const string GRADE_RANGE = "(0-5)";

// Allows teacher to input a single student's grade.
int inputStudentGrade(){
	int grade;
	
	while(true) {
		cout << "Enter a student's grade " << GRADE_RANGE << endl;
	    cout << "Enter " << STOP << " to stop entering grades" << endl;
		
		cin >> grade;
		
		if (grade == STOP ||
		    (grade >= MINIMUM_GRADE && grade <= MAXIMUM_GRADE)) {
		  break;
		}
		
		cout << "That is not a valid grade " << GRADE_RANGE
		     << " or stop signal (" << STOP << ")" << endl;
	}
	
	return grade;
}

// Allows teacher to input grades for all students in a class.
void inputClassGrades(int gradeCount[GRADES]){
    int grade;
	
	while(true) {
		grade = inputStudentGrade();
		
		if (grade == STOP) {
			break;
		}
		
		gradeCount[grade]++;
	}
}

void displayHistogram(int gradeCount[GRADES]) {
	for (int i = 0; i < GRADES; i++) {
		cout << gradeCount[i] << "grade(s) of " << i << endl;
        }
}

int main(){
	int gradeCount[GRADES] = {0, 0, 0, 0, 0, 0};
	
	inputClassGrades(gradeCount);
        displayHistogram(gradeCount);

	return 0;
}