Thread: A little assignment involving arrays.

Whats happening in sum[thirteen] = multiply * thirteen;? All elements in an array are numbered, so why doesn't sum[thirteen] give me an exception message or something?

Kevin I am trying to follow your advice but not understanding line 8

sum[thirteen] = multiply * thirteen;

is really being a hurdle. I really don't understand that line at all, it was used in another project from the Jin24 so I thought I'd try it and see if it works.

When I use the code below sum[0] is always being set to 0.

class ThirteenArray {
    public static void main(String[] args){
        //Hour 9, Second activity.
        int multiply = 13;
        int[] sum = new int[400];
        //int num = 1;
       for(int thirteen = 0; thirteen < sum.length; thirteen++){
            sum[thirteen] = multiply * thirteen;
            System.out.print(" " + sum[thirteen]);
            //num++;
        }
        System.out.print("\n " + sum[0]);
    }
}

Output:
0 13 26 39 52 65 78 91.... 5148 5161 5174 5187
0BUILD SUCCESSFUL (total time: 1 second)

Hopefully you can print the table (2X1=2, 2X2=4 ..............), just use a little logic and relationships of the indexes being transfered through the loop and you will be able to do that...

Originally Posted by Melawe

When I use the code below sum[0] is always being set to 0.

class ThirteenArray {
    public static void main(String[] args){
        //Hour 9, Second activity.
        int multiply = 13;
        int[] sum = new int[400];
        //int num = 1;
       for(int thirteen = 0; thirteen < sum.length; thirteen++){
            sum[thirteen] = multiply * thirteen;
            System.out.print(" " + sum[thirteen]);
            //num++;
        }
        System.out.print("\n " + sum[0]);
    }
}

Output:
0 13 26 39 52 65 78 91.... 5148 5161 5174 5187
0BUILD SUCCESSFUL (total time: 1 second)

The reason is you start with 0 and anything when comes to multiply with zero, results in zero.

What would happen if you started with

sum[thirteen] = multiply * (thirteen + 1);

?

The first value of thirteen is 0, so sum[0] = multiply * 0 = 0 the way you have it. (I think Mr. 777 said that above already.)

If you change it like I recommend you do, it will do:

sum[0] = multiply * (0+1) = 13

Sorry I haven't been posted any updates. PC is acting up keeps giving a nasty "Error loading os." message. So I've been backing up and hadn't much time for coding. I did get a chance to update the code and I think I got it this time.

class ThirteenArray {
    public static void main(String[] args){
        //Hour 9, Second activity.
        int thirteen = 1;
        int[] sum = new int[400];
       for(int multiply = 0; multiply < sum.length; multiply++){
            sum[multiply] = thirteen * 13;
            System.out.print(" " + sum[multiply]);
            thirteen++;
        }
    }
}

Output: 13 26 39 52....5161 5174 5187 5200

Does that do it with out anything unnecessary?

Changed the names of the variables to something more suitable.

class ThirteenArray {
    public static void main(String[] args){
        //Hour 9, Second activity.
        int multiply = 1;
        int[] sum = new int[400];
       for(int aryelement = 0; aryelement < sum.length; aryelement++){
            sum[aryelement] = multiply * 13;
            System.out.print(" " + sum[aryelement]);
            multiply++;
        }
    }
}

Anything I could do better?

Thanks all!