// This program has several examples of different kinds of loops.

import java.util.*;

public class Loops {
    public static void main(String[] args) {
        // prints 1, 2, 3, ..., 9, 10
        printNumbers(10);

        simpleWhile();

        Scanner console = new Scanner(System.in);
        sumNumbers(console);
    }

    // prints the numbers 1 to max separated by commas
    public static void printNumbers(int max) {
        // below is one solution to the fencepost problem that prints the first
        // number before the loop
        System.out.print(1);
        for (int i = 2; i <= max; i++) {
            System.out.print(", " + i);
        }
        System.out.println();

        // below is a second solution to the fencepost problem that prints the
        // final number after the loop
        /*
        for (int i = 1; i <= max - 1; i++) {
            System.out.print(i + ", ");
        }
        System.out.println(max);
        */
    }

    // simple while loop example that doubles a number until it is greater than
    // 200
    public static void simpleWhile() {
          int number = 1;
          while (number <= 200) {
              System.out.print(number + " ");
              number = number * 2;
          }
          System.out.println(number);
    }

    // example of a sentinel loop; user is prompted for numbers to sum until
    // sentinel value of -1 is entered
    public static void sumNumbers(Scanner console) {
        int sum = 0;
        System.out.print("next int (-1 to quit)? ");
        int number = console.nextInt();
        while (number != -1) {
            sum = sum + number;
            System.out.print("next int (-1 to quit)? ");
            number = console.nextInt();
        }
        System.out.println("sum = " + sum);
    }
}