Noob Problem

[Joseph Quintana]

Hello Coderanch forum members. This is my firts time ever posting on here. I'm a relative beginner who's taken a lot of introductory programming classes but never became good at any one of them (probably because I was on to the next one). That being said, now I pretty much don't remember any languages and all the courses I've taken were a waste of time. The language that I enjoyed the most was always Java! I'm here to improve as much as I can.

Here's my problem. I was tasked with creating a simple drivers exam test program that consisted of 20 questions that needed to be answered with an uppercase "A-D." At the end of the test I display whether or not you've passed or failed and the percent correct. The pass/fail portion works, but for some reason the percent correct always stays at 0%.

Can someone help me figure out what's wrong here?

Here's the code:

import java.util.Scanner;
import java.text.DecimalFormat;

public class DriversExam {
	

	public static void main(String[] args) {
		
		
		//responses array will hold the users answers to the questions
		char[] responses = new char[20];
		
		//char answer will hold the converted char entered by the user
		char answer;
		
		//correctAnswers int is used to hold the number correct found by the totalCorrect method
		int correctAnswers;
		
		//String holder will hold the strings entered by the user before converted to a char
		String holder;
		
		//Description to user
		System.out.println("The following 20 Driving questions must be answered with an uppercase letter A, B, C, or D.");
		System.out.println("Your percent correct and pass or fail status will be displayed upon conmpletion.");
		
		//new Scanner object
		Scanner keyboard = new Scanner(System.in);
		
		//I decided to use a for loop to run through the 20 questions
		for (int i = 0; i < 20; i++)
		{
			//a plus 1 is added to i to account for the 0 subscript
			System.out.println("Answer question #" + (i + 1) + " ");
			//holder is holding the string entered
			holder = keyboard.nextLine();
			//the answer variable stores the first char entered by the user
			answer = holder.charAt(0);
			
			//the responses array is assigned the character entered by the user until it reaches 20
			responses[i] = answer;
		}
		
		//calls the totalCorrect method and passes the array responses to it.
		correctAnswers = totalCorrect(responses);
		
		passed(correctAnswers);
		
	}
	
	//method to calculate the total correct answers entered by the user
	public static int totalCorrect(char responses[])
	{
		//testScores array holds the correct scores to the test
		char[] testScores = {'B', 'D', 'A', 'A', 'C', 'A', 'B', 'A', 'C', 'D', 'B', 'C', 'D', 'A', 'D', 'C', 'C', 'B', 'D', 'A'};
		//created to hold the loop number
		int index = 0;
		//accumulator created to add up the total correct answers
		int numCorrect = 0;
		
		//while loop goes through all the answers and compares them to the answer key. the numCorrect is incremented for every right answer.
		while (index < responses.length)
		{
			if (responses[index] == testScores[index])
			{
				numCorrect += 1;
			}	
			index++;
		}
	
		return numCorrect;
	}
	
	//method to calculate whether or not the user has passed the exam
	public static boolean passed(int numCorrect)
	{
		DecimalFormat percent = new DecimalFormat("%#0.#");
		
		//if the numCorrect is greater than 15 the user passes the test
		if (numCorrect >= 15)
		{
			System.out.println("You PASSED the test!!");
			//variable created to hold the percentage correct for the user
			double percentage = (numCorrect/20) * 100;
			System.out.println("Your percent correct is: " + percent.format(percentage));
			return true;
		}
		//if the user gets less than 15 they fail the test
		else {
			System.out.println("Sorry you FAILED the test!!");
			//variable created to hold the percentage correct for the user
			double percentage = (numCorrect/20) * 100;
			System.out.println("Your percent correct is: " + percent.format(percentage));
			return false;
		}
		
		
			
	}
	
}

[Greg Brannon]

In integer math, what is numCorrect / 20 when numCorrect <= 20?

[Jeff Verdegan]

int / int gives an int result, so, for instance 9 / 10 has a result of 0. Converting to a double after the fact is too late. You need to have at least one operand be a double to start with.

int score = 12;
double percentage = (score / 20.0) * 100.0;

[Matthew Brown]

And Welcome to The Ranch, Joseph!

[Joseph Quintana]

Jeff Verdegan wrote:int / int gives an int result, so, for instance 9 / 10 has a result of 0. Converting to a double after the fact is too late. You need to have at least one operand be a double to start with.

int score = 12;
double percentage = (score / 20.0) * 100.0;

Thank you Jeff. I knew it was something simple. It usually is. With all the math I've taken, percentages have always been an achilles heel of mine.

Everything works properly now.

[Joseph Quintana]

Matthew Brown wrote:And Welcome to The Ranch, Joseph!

Thank you! Happy to be here.

My problem was solved in minutes.