printing an array with a for-loop

Question

I've build an array with 10 plurals of 7 and am now trying to print it in reversed order with a for loop. but my program seems to be ignoring this code. I've no issues printing it in regular order with a for or a for each loop. What is wrong in this piece of code?

int[] numbers = new int[10];
for (int i = 0; i < numbers.length; i++) {
     numbers[i] = (int) (Math.random() * 10) * 7;
}
for (int i = numbers.length; i == 0; i--) {
     System.out.println(numbers[i]);
}
System.out.println("---");
for (int i = 0; i < numbers.length; i++) {
     System.out.println(numbers[i]);
}

In the second loop, myabe you intend: (int i = numbers.length; i > 0; i--) — alepuzio
– alepuzio, Commented Dec 11, 2013 at 15:54

Ivaylo Strandjev · Accepted Answer · 2013-12-11 15:54:20Z

3

An array of size N in java has its indexes ranging from 0 to N-1. So in fact numbers.length is out of bounds - the last element in numbers is with index numbers.length - 1. Also not your condition should be i >= 0 instead of i==0, otherwise your cycle will never be executed for an array of size greater than 1.

answered Dec 11, 2013 at 15:54

Ivaylo Strandjev

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2 Comments

YoNuevo Over a year ago

thank! I knew about the Array sizes and index ranges but I completely forgot to take it into account for my code. Netbeans didnt show me any error either, nor did java when I ran it. I've actually done this exercise before (but left the code somewhere else) and had no issues that time. Very frustrating to have them now! I did not know about the conditions.

Ivaylo Strandjev Over a year ago

@YoNuevo I believe it is more important to understand why the conditions are like this. If you understand how a for cycle works it will be way easier for you to debug your own code.

zavg · Accepted Answer · 2013-12-11 15:59:56Z

1

It should be

for (int i = numbers.length - 1; i >= 0; i--) {

in your reverse order loop.

edited Dec 11, 2013 at 15:59

answered Dec 11, 2013 at 15:53

zavg

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3 Comments

Ivaylo Strandjev Over a year ago

Please take another look at the cycle. There is one more error that will prevent it from running correctly.

YoNuevo Over a year ago

I did forget about the '-1' but I've added it to the code now and it still doesn't print anything. I dont understand why this program is ignoring this piece of code. It doesnt show my any error either.

Ivaylo Strandjev Over a year ago

@YoNuevo take a look at my answer you should also replace i==0 with i >= 0.

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