import java.util.Scanner; // Needed for the Scanner class

public class DriverExam
{
public static void main(String[] args)
{
// Create an array init to 0
char[] answerKey = {'B','D','A','A','C','A','B','A','C','D','B','C','D','A','D','C','C','B','D','A'},
studentAns = new char[answerKey.length];

double passing = 65.0;

// Create a Scanner object to read input.
Scanner keyboard = new Scanner(System.in);
String input; // To hold a line of input
char answer; // To hold a single character;

// Ask the user to enter a student's answers.
for (int i = 0; i < answerKey.length; i++)
{
System.out.print("What is the answer to question #" + (i + 1) + "? ");
input = keyboard.nextLine();
studentAns[i] = input.charAt(0);
}

// Demonstrate the totalCorrect() function.
System.out.println("Total correct: " + totalCorrect(studentAns, answerKey) );


// Demonstrate the totalncorrect() function.
System.out.println("Total incorrect: " + totalIncorrect(studentAns, answerKey) );


// Demonstrate the questionsMissed() function.
int[] missedQuestions = questionMissed(studentAns, answerKey);
printMissedQuest(missedQuestions);


// Demonstrate the passed() function.
if (passed(studentAns, answerKey, passing) )
System.out.print("You passed!");
else
System.out.print("You failed. Better luck next time.");

System.out.println(" Passing is " + passing + "%.");


}

// Returns true if the student passed the exam or false if the student failed.
private static boolean passed(char[] exam, char[] answers, double passing)
{
double percentageCorrect = (totalCorrect(exam, answers) / answers.length * 100);
return (percentageCorrect >= passing);
}

// Returns the total number of correctly answered questions
private static int totalCorrect(char[] exam, char[] answers)
{
int numCorrect = 0;
for (int i = 0; i < exam.length; i++)
if (exam[i] == answers[i])
numCorrect++;

return numCorrect;
}

// Returns the total number of incorrectly answered questions
private static int totalIncorrect(char[] exam, char[] answers)
{
int numIncorrect = 0;
for (int i = 0; i < exam.length; i++)
if (exam[i] != answers[i])
numIncorrect++;

return numIncorrect;
}

// An int array containing the question numbers of the questions that the student missed.
private static int[] questionMissed(char[] exam, char[] answers)
{
int[] missedQuestions = new int[exam.length];
for (int i = 0; i < exam.length; i++)
if (exam[i] != answers[i])
missedQuestions[i] = (i+1);

return missedQuestions;
}

// Prints the values in a char array.
private static void printArray(char[] exam)
{
for (int row = 0; row < exam.length; row++)
{
System.out.print(exam[row] + " ");
}
System.out.println();
}

// Prints the values in an int array that are non-zero.
private static void printMissedQuest(int[] missedQ)
{
System.out.print("Questions missed: ");
for (int row = 0; row < missedQ.length; row++)
{
if (missedQ[row] != 0)
System.out.print(missedQ[row] + ", ");
}
System.out.println();
}

}