Question

I’m trying to make a 5 by 10 table using a double array. The first box should be blank, then the rest numbered 2-50.

I have this so far but it is not working.

int array[][] = new int[5][10];
      for(int row=1; row<5;row++){
         for(int col=1;col<10;col++)
            array[row][col] = row*col;}
         System.out.println(array);

Answer 1

row * col cannot give you consecutive numbers from 2 to 50. And in your code, you are not just leaving the first box, but you are leaving out first row and first column completely.

You should run the loop normally from 0 to max. And for [0][0], don’t print anything.

Also, for printing from 2 to 50, just have a count variable which starts with 2, and after printing it, increment it by 1.

Here’s the modified code: –

int array[][] = new int[5][10];
int count = 2;

for(int row=0; row<5;row++){
    for(int col=0;col<10;col++) {
        if (row == 0 && col == 0) {
            continue;
        }
        array[row][col] = count++;
    }
}
for (int[] inner: array) {
    System.out.println(Arrays.toString(inner));
}

OUTPUT : –

[0, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
[21, 22, 23, 24, 25, 26, 27, 28, 29, 30]
[31, 32, 33, 34, 35, 36, 37, 38, 39, 40]
[41, 42, 43, 44, 45, 46, 47, 48, 49, 50]

NOTE: –

Since you want your first box to be blank, you can’t use Arrays.toString here. You would have to use one more loop, and print your array in simple ways. And when your indices are [0][0], just sysout("");