Making an array that prints multiples of a given number

Question

I need help making an array that prints out multiples of a given number. The output looks like this:

Enter a positive integer: 8
Test array: 1 1 2 3 5 8 13
Counting up: 1 2 3 4 5 6 7 8
Counting down: 8 7 6 5 4 3 2 1
The first 8 multiples of 5: 5 10 15 20 25 30 35 40
The first 8 multiples of 10: 10 20 30 40 50 60 70 80

This is what I have so far in code:

//Creates an array that counts up to the user input
public static int[] countUp(int n){
    int [] temp = new int[n];
    for(int i=0; i<n; i++){
        temp[i] = i+1;
    }
    return temp;
}

//Creates an array that counts down to the user input
public static int[] countDown(int n){
    int [] temp = new int[n];
    for(int i=0; i<temp.length; i++){
        temp[i] = n--;
    }
    return temp;
}

//Creates an array that gets n amount of multiples of 5
public static int[] getMultiplesOfFive(int n){
    int [] temp = new int[n];
    for(int i=0; i<temp.length; i++){
        temp[i] = n+5;
    }
    return temp;
}

//Creates an array that gets n amount of multiples of 10
public static int[] getMultiplesOfTen(int n){
    int [] temp = new int[n];
    for(int i=0; i<temp.length; i++){
        temp[i] = n+10;
    }
    return temp;
}
}

However my output looks like this:

Enter a positive integer: 8
Test array: 1 1 2 3 5 8 13 
Counting up: 1 2 3 4 5 6 7 8 
Counting down: 8 7 6 5 4 3 2 1 
The first 8 multiples of 5: 13 13 13 13 13 13 13 13 
The first 8 multiples of 10: 18 18 18 18 18 18 18 18

Obviously the problem is in the last two arrays called getMultiplesofFive and getMultiplesofTen. I'm just not sure how to create a loop that gives me the correct output. Thank you so much!

pczeus · Accepted Answer · 2016-03-16 02:14:36Z

2

In your multiply methods, you were not multiplying. Try this:

    //Creates an array that gets n amount of multiples of 5
    public static int[] getMultiplesOfFive(int n){
        int [] temp = new int[n];
        for(int i=0; i<temp.length; i++){
            temp[i] = (i+1)*10;
        }
        return temp;
    }

    //Creates an array that gets n amount of multiples of 10
    public static int[] getMultiplesOfTen(int n){
        int [] temp = new int[n];
        for(int i=0; i<temp.length; i++){
            temp[i] = (i+1)*10;
        }
        return temp;
    }

Adding (i+1) since the index will start at 0 and you want to stat with n*1

answered Mar 16, 2016 at 2:14

pczeus

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3 Comments

Andreas Brunnet Over a year ago

You might also just do int i = 1; i <= n;

pczeus Over a year ago

True @AndreasBrunnet. But then you still have to reference the array index and in that case subtract 1: temp[i-1] ='. Or, you could skip the i++ increment and do that in the array index: for(int i = 1; i < temp.length;){ temp[i++] = ...'. Either way somewhere you have to make the adjustment.

Andreas Brunnet Over a year ago

Damn it forgot about the index. Happens when it's late one is tired... Either way your answer should be marked ;)

Andreas Brunnet · Accepted Answer · 2016-03-16 02:27:06Z

0

Your problem is that you keep on calculating the same results. You pass "n" into your method and you store the result of n + 10 in every index (i) of your array.

What you want is something like this (just using the times 5 example):

int[] temp = new int[n];
for(int i = 1; i <= n; i++)
{
    temp[i-1] = i * 5;
}

edited Mar 16, 2016 at 2:27

answered Mar 16, 2016 at 2:14

Andreas Brunnet

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