Printing a large character from small characters

Question

I am trying to get a program to print a 'X' with x's. ie:

xxx      xxx
 xxx    xxx
  xxx  xxx
   xxxxxx
  xxx  xxx
 xxx    xxx
xxx      xxx

This is what I have done so far:

import java.util.Scanner;
public class CustomXfactor {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        boolean quit = false;
        int i=0, a=0, c=0;

        System.out.printf("length must be between 16 and 120\n");

        //Ask for desired length
        System.out.printf("Please enter the length (0  to exit):\n");
        int length = in.nextInt();
        int spaces = (length-length+1), //Calculate spaces before the first leg
                innerSpaces = (length-6); //Calculate the inner spaces -6
                                         //because there is 6 Xs which are 
                                         //the form the legs

        while(!quit){
            //Print first half of the X
            for (i=0;i<(length/2);i++){

                //First XXX leg
                System.out.printf("XXX");

                //Space between the legs
                for (a=length-6;a<innerSpaces;a++){
                    System.out.printf(" ");
                }
                //Second XXX leg
                System.out.printf("XXX\n");

                //SPACES 
                for (c=0;c<(spaces);c++){
                System.out.printf(" ");
                }
                spaces++;
                innerSpaces--;
            }
            quit = true; //Change boolean to break while loop
        }//END of while loop
    }//END of method main
}//END end of class CustomXfactor

My math issue is in line 26. I am not getting the loop to print the correct spaces between the legs of the X, and then taking one away as it loops.

As you can see, this is only half of the X, but once I got this side, I can reverse it to generate the rest.

I would appreciate some help on my math there.

Answer 1

Divide-and-conquer approach will make your work easier to understand and easier to solve. Think of the ways of handling the printing issues of the trailing spaces of each line as well as the spaces between "XXX" unit Strings. I didn't want to solve your problem completely, but I think you should take a look at this code to understand what you are missing. With this code, you get the half of the desired output in a String array. And traversing it in order and then in reverse order will give you the correct output.

public static void main(String[] args) {
    String unit = "XXX"; // Unit String.
    int width = 21; // You can get this input from user.
    int betweenSpaces = width - 2 * unit.length(), trailingSpaces = 0;

    String[] lines = new String[(width - 2 * unit.length()) / 2 + 1];

    for (int i = 0; i < lines.length; i++) {
        lines[i] = "";
        lines[i] = helper(trailingSpaces, lines[i], unit)
                 + helper(betweenSpaces, lines[i], unit);

        betweenSpaces -= 2; // Decrement space count by 2.
        trailingSpaces += 1; // Increment trailing space count by 1.
    }

    // Printing lines array.
    for (String str : lines)
        System.out.println(str);
    for (int i = lines.length - 2; i >= 0; i--)
        System.out.println(lines[i]);
}

public static String helper(int count, String ref, String unit) {
    for (int j = 0; j < count; j++)
        ref += " ";
    return ref += unit; // 2nd unit string appended.
}

Output:

XXX               XXX
 XXX             XXX
  XXX           XXX
   XXX         XXX
    XXX       XXX
     XXX     XXX
      XXX   XXX
       XXX XXX
      XXX   XXX
     XXX     XXX
    XXX       XXX
   XXX         XXX
  XXX           XXX
 XXX             XXX
XXX               XXX