Can someone explain to me the 2nd for loop .. I already understand the first one.. thanks

Question

I'm creating a java project called magicsquare and I've searched online on how to do it. Now, I'm trying to understand how the 2nd loop works, I know that it prints and align the magic square, but I don't know the details. I already know the first one. I would really appreciate if someone explains to me the 2nd loop. Thanks!

import java.util.*;
public class Magicsquare {

        public static void main(String[] args) { 
            Scanner input = new Scanner(System.in);

     try{
            int N;
            System.out.print("Enter a number to create a Magic Square: ");
            N=input.nextInt();

            if (N % 2 == 0){
                System.out.print("N must be an Odd number!");
            }

            else{

            int[][] magic = new int[N][N];
            int row = N-1;
            int col = N/2;
            magic[row][col] = 1;

            for (int i = 2; i <= N*N; i++) {
                if (magic[(row + 1) % N][(col + 1) % N] == 0) {
                    row = (row + 1) % N;
                    col = (col + 1) % N;
                }
                else {
                    row = (row - 1 + N) % N;

                }
                magic[row][col] = i;
            }


            for (int c = 0; c < N; c++) {
                 for (int r = 0; r < N; r++) {
                    if (magic[r][c] < 10)  System.out.print(" ");  // for alignment
                    if (magic[r][c] < 100) System.out.print(" ");  // for alignment
                    System.out.print(magic[r][c] + " ");
                }
                System.out.println();
          } 
       }main (null);
    }catch (Exception e){
        System.out.print("Invalid Input!");
    }
  }
}

Answer 1

Well, first the obvious. The part about < 10 and < 100: if a number is between 0 and 9, it's only going to print out one digit. If it's between 10 and 99, it's going to print out two. And if it's between 100 and 999, it'll print out using three digits. (It seems as if this code is written to assume it will only encounter numbers between 0 and 999. Generally speaking, it's best to ensure that somehow rather than just hope.)

So, with the if statements and their extra spaces, a "5" will print out as " 5" (note the two leading spaces for a total of three characters). 25 will print out as " 25" (again, three characters) and 125 as "125" (three digits again). Since all of the numbers print out using three characters, everything will line up neatly in columns.

What confuses me is that you're iterating over c first, then r. This seems to say that you're printing out the first column on a single row on the screen, then the second column as a second row, and the third column as a third row. I.e. the whole thing has been rotated on a diagonal. But maybe that's just a naming issue.