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Thread: Understanding array operators

  1. #1
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    Default Understanding array operators

    Hello!

    I am having trouble understanding how thing work with arrays specificly what the "=" operator represents. I've written a really simple code and I'm trying to fully understand what is happening, I am having a few doubts and some help would be appreciated. Thank you!

     
    public class test {
    	public static void main(String[]args) {
     
    		int[] numbers = {1,2,3,4,5};
     
    		int temp;
     
    		int start = 0;// first number in the array (1)
     
    		int end = numbers.length -1;//last number in the array(5)
     
    		while(start < end) {// keep going until the numbers "collide"
    			temp = numbers[start];//temp now holds the value of start(1)
     
    			numbers[start] = numbers[end];// this is the part that confuses me
     
    			numbers[end] = temp;//this as well
     
    			start = start + 1;// increase the value of start by 1
    		    end = end -1;// decrease the value of end by 1
     
    		}
     
    		Out.println(java.util.Arrays.toString(numbers));
    	}
    }

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Understanding array operators

    Think of an array as a line of buckets that can only hold one type of thing, say fruit and only one at a time.
    If there are 5 buckets in front of you and from left to right (indexes 0 to 4)
    and the buckets contain an apple, orange, pear, peach and banana.
    What is in the bucket with index = 1? (an orange)
    numbers[start] = numbers[end];// this is the part that confuses me
    What if you copy the contents of bucket 3 (peach) to bucket 2? Now there are two buckets with peaches. The pear was replaced by a peach.
    Replace the specific numbers 3 and 2 with the contents of variables like end (=3) and start(=2).

    Work through the program's steps with paper and pencil to see what it does.
    If you don't understand my answer, don't ignore it, ask a question.

  3. The Following User Says Thank You to Norm For This Useful Post:

    arhzz (September 16th, 2020)

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    Default Re: Understanding array operators

    Great answer thank you!

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