Computer Science 202
Introduction to Programming

Fall 2012, The College of Saint Rose

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Sum1ToNBetter BlueJ Project

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Sum1ToNBetter Source Code

The Java source code for Sum1ToNBetter is below. Click on a file name to download it.

Sum1ToNBetter.java

/*
 * Example Sum1ToN - a method that returns the sum of the integer
 * values from 1 to a given number -- now using a more efficient
 * formula for the computation
 *
 * Jim Teresco, The College of Saint Rose, CSC 202, Fall 2012
 *
 * $Id: Sum1ToNBetter.java 1995 2012-11-27 01:39:43Z terescoj $
 */

public class Sum1ToNBetter {

    // our method looks like the ones we had before, except this
    // one now returns an int
    public static int sumNumbersTo(int limit) {

        // we just compute this using our mathematical formula
        return limit * (limit+1) / 2;
    }

    public static void main(String[] args) {

        // for this example, we will just print out a few of these sums
        int firstSum = sumNumbersTo(10);
        System.out.println("The sum of the numbers 1-10 is " + firstSum);

        int secondSum = sumNumbersTo(82);
        System.out.println("The sum of the numbers 1-82 is " + secondSum);

        int thirdSum = sumNumbersTo(96352);
        System.out.println("The sum of the numbers 1-96352 is " + thirdSum);

        // or we can use this within a loop
        for (int number = 1; number <= 9; number++) {
            // and we can use the value as part of a printout or any other expression
            // if we do not want or need to save it in a variable
            System.out.println("The sum of the numbers 1-" + number + 
                " is " + sumNumbersTo(number));
        }
    }
}