/* 9/23/2019
 
 */
import java.util.Scanner;

/** Problem: read in and print out a number of test grades 
  */
public class Testgrades {
  
  public static void main(String[] args) { 

      int numGrades = 5;
      Scanner scanner = new Scanner(System.in);
      String answer;
      
      // use a while loop to read in 5 grades
      int i=1;
      while (i <= numGrades) {
        System.out.println("Enter a grade: ");
        double grade = scanner.nextDouble();
        System.out.println("Grade " + i + " " + grade);
        i++; // counter
      }
      System.out.println("Fell out of loop, i is: " + i);
      // What if pgmer does not know the number of grades?
      // attempt 1: ask the user how many grades there are
      System.out.println("How many grades are there? ");
      numGrades = scanner.nextInt();
      i=1;
      while (i <= numGrades) {
        System.out.println("Enter a grade: ");
        double grade = scanner.nextDouble();
        System.out.println("Grade " + i + " " + grade);
        i++; // counter
      }
      // attempt 2a: user doesn't know in advance how many grades there are
      // keep asking user whether there is another grade
      answer = "yes";
      boolean done = false;
      while (!done) {
        // process a grade
        System.out.println("Enter a grade: ");
        double grade = scanner.nextDouble();
        System.out.println("Grade " + grade);
        // figure out whether the loop should run again
        System.out.println("Do you have another grade? (yes/no)");
        answer = scanner.next();
        if (answer.charAt(0)!='y') {
            done = true;
        }
        else ;
      }
    // attempt 2b: user doesn't know in advance how many grades there are
      // keep asking user whether there is another grade
      // gets rid of boolean variable
      answer = "yes";
      while (answer.charAt(0)=='y' || answer.charAt(0)=='Y') {
      //to run until user enters an answer that begins with 'n' or 'N'
      //while(answer.charAt(0)!='n' && answer.charAt(0)!='N') {
        // process a grade
        System.out.println("Enter a grade: ");
        double grade = scanner.nextDouble();
        System.out.println("Grade " + grade);
        // figure out whether the loop should run again
        System.out.println("Do you have another grade? (yes/no)");
        answer = scanner.next();
      }
      
      // attempt 3: in the case that it is not practical to ask the user,
      // use a sentinel value (e.g. -1)
      // and a structured read loop
      System.out.println("Enter a grade, -1 to finish: ");
      double grade = scanner.nextDouble();
      while(grade!=-1){      
           System.out.println("Grade " + grade);
           System.out.println("Enter a grade, -1 to finish: ");
           grade = scanner.nextDouble();
      }
      // attempt 4: read until end of input 
      // prompt outside 
      System.out.println("Enter a grade, end of input symbol to finish: ");
      while(scanner.hasNext()){      
           grade = scanner.nextDouble();
           System.out.println("Grade " + grade);
           System.out.println("Enter a grade, end of input symbol to finish: ");
      }
      scanner.close();
  }
}