Home/ Questions/How to avoid the error "write a loop that sets newscores to oldscores shifted once left, with element 0 copied to the end"?
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Elina Roy
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Asked: 2022-05-18T16:06:37+00:00 In:

How to avoid the error “write a loop that sets newscores to oldscores shifted once left, with element 0 copied to the end”?

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I’m trying to run a new project. I do a couple of things like this:

public class StudentScores {
  public static void main (String [] args) {
  final int SCORES_SIZE = 4;
  int[] oldScores = new int[SCORES_SIZE];
  int[] newScores = new int[SCORES_SIZE];
  int i = 0;
 
  oldScores[0] = 10;
  oldScores[1] = 20;
  oldScores[2] = 30;
  oldScores[3] = 40;
 
  for (i = 0; i < SCORES_SIZE - 1; i++) {
  newScores[3] = oldScores[0];
  newScores[i] = oldScores[i + 1]; 
  }
 
  for (i = 0; i < SCORES_SIZE; ++i) {
  System.out.print(newScores[i] + " ");
  }
  System.out.println();
 
  return;
  }
  }

But in my program, I am getting the warning:

Write a loop that sets newScores to oldScores shifted once left, with element 0 copied to the end. Ex: If oldScores = {10, 20, 30, 40}, then newScores = {20, 30, 40, 10}.

Note: These activities may test code with different test values. This activity will perform two tests, the first with a 4-element array (newScores = {10, 20, 30, 40}), the second with a 1-element array (newScores = {199}). See How to Use zyBooks.

Also note: If the submitted code tries to access an invalid array element, such as newScores[9] for a 4-element array, the test may generate strange results. Or the test may crash and report "Program end never reached", in which case the system doesn't print the test case that caused the reported message.

Can someone explain why the “ write a loop that sets newscores to oldscores shifted once left, with element 0 copied to the end.” issue happened? Where have I gone wrong? Thank you!

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2 Answers

  1. Best Answer
    Expert

    The cause:  When SCORES SIZE == 1, the for loop that copies values from oldscores to newscores never runs since SCORES SIZE - 1 == 0, and 0 < 0 is false right away. This is what causes the issue to arise.

    Solution:

    Shift the newScores[SCORES_SIZE - 1] = oldScores[0]; the line which is outside the for loop:

    for (i = 0; i < SCORES_SIZE - 1; i++) {
newScores[i] = oldScores[i + 1];
}
newScores[SCORES_SIZE - 1] = oldScores[0];

     

    • 0

  2. If you assume that the only other check is one array of length one, then simply use this 

    if(oldscores.length==1)
{newscores[0]=oldscores[0];
System.out.println(newscores[0]);
}

    Or, you can do it even simpler. 

    if(oldscores.length==1)
{
 System.out.println(oldscores[0]);
}
    • 9

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