// Introduction to Software Testing
// Authors: Paul Ammann & Jeff Offutt
// Chapter 9; page ??
// Can be run from command line
// No JUnit tests at this time.

public class Sum
{
  /**
    * Sum values in an array
    * 
    * @param x array to sum
    * @return sum of values in x
    * @throws NullPointerException if x is null
    */
   public static int sum(int[] x)
   {
      int s = 0;
      for (int i=0; i < x.length; i++)
      {
         s = s + x[i];
         // s = s - x[i];
      }
      return s;
   }
   
   public static void main (String []argv)
   {  // Driver method for sum
      // Read an array from standard input, call sum()
      int []inArr = new int [argv.length];
      if (argv.length == 0)
      {
         System.out.println ("Usage: java Sum v1 [v2] [v3] ... ");
         return;
      }
   
      for (int i = 0; i< argv.length; i++)
      {
         try
         {
            inArr [i] = Integer.parseInt (argv[i]);
         }
         catch (NumberFormatException e)
         {
            System.out.println ("Entry must be a integer, using 1.");
            inArr [i] = 1;
         }
      }
   
      System.out.println ("The sum is: " + sum (inArr));
   }
}