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Thread: Display patterns using loops

  1. #1
    Member John Joe's Avatar
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    Exclamation Display patterns using loops

    Used nested loops that display following patterns

                    *
                   ***
                  *****
                   ***
                    *

    I only able to have this, after that stucked.
    for (int i = 0; i < 5; i++) {
        for (int j = 0; j <= i * 2; j++) {
             System.out.print("*");
    	}
             System.out.println();
    	}
    Last edited by John Joe; January 17th, 2018 at 11:59 AM. Reason: change QUOTE to CODE
    Whatever you are, be a good one

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Display patterns using loops

    Can you post the program's current output to show what it does?

    Describe the pattern of the output:
    how many lines are printed?
    what goes on each line?
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
    Member John Joe's Avatar
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    Default Re: Display patterns using loops

    Current output is
    *
    ***
    *****
    *******
    *********
    Last edited by John Joe; January 17th, 2018 at 12:00 PM. Reason: change QUOTE to CODE
    Whatever you are, be a good one

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Display patterns using loops

    Can you describe the pattern of the desired output:
    how many lines are printed?
    what goes on each line?
    How does what is printed on a line relate to what line is being printed?
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
    Member John Joe's Avatar
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    Default Re: Display patterns using loops

    Thanks for your reply Norm, I actually want it to print a diamond.
    I have solved it.

         for (int i = 1; i < 5; i += 2) {
    			for (int j = 0; j < 4 - i / 2; j++)
    			   System.out.print(" ");
     
    			for (int j = 0; j < i; j++)
    			  System.out.print("*");
     
    			System.out.println();
    		}
     
    		for (int i = 5; i > 0; i -= 2) {
    			for (int j = 0; j < 4 - i / 2; j++)
    				System.out.print(" ");
     
    			for (int j = 0; j < i; j++)
    				System.out.print("*");
     
    			System.out.println();
    		}
    Whatever you are, be a good one

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: Display patterns using loops

    want it to print a diamond.
    I have solved it.
    You could Wrap the post of the output in code tags to preserve the leading spaces so we can see its shape.

    Glad you solved it.

    Note: The code has too many "magic numbers". Can you change it so the number of lines to print is in a variable and then the contents of that variable is used to control the logic?
    Then make it a method and execute it with different values.
    If you don't understand my answer, don't ignore it, ask a question.

  7. #7
    Member John Joe's Avatar
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    Default Re: Display patterns using loops

    You could Wrap the post of the output in code tags to preserve the leading spaces so we can see its shape.
    This is the output
       * 
      * * 
     * * * 
      * * 
       *
    What did you mean "magic numbers" ?
    Whatever you are, be a good one

  8. #8
    Super Moderator Norm's Avatar
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    Default Re: Display patterns using loops

    All the 5s and 4s should be replaced by variables. The 2 is ok because it is used to get half of a value and would never change.
    If you don't understand my answer, don't ignore it, ask a question.

  9. #9
    Member John Joe's Avatar
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    Default Re: Display patterns using loops

    Don't understand Did you mean it would be better if I assign a variable to 4 and 5 ?
    Whatever you are, be a good one

  10. #10
    Super Moderator Norm's Avatar
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    Default Re: Display patterns using loops

    Replace the numbers 4 and 5 with variables. Don't hard code numbers in the code.
    Then write a method that takes the number of rows as its arg.
    Call the method with different values for the number of rows.
    If you don't understand my answer, don't ignore it, ask a question.

  11. #11
    Member John Joe's Avatar
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    Lightbulb Re: Display patterns using loops

    I think you mean this ?

    public class Example {
     
    	public static void main(String[] args) {
    		Scanner input = new Scanner(System.in);
    		System.out.print("Key in the row you want it to display: ");
    		int k = input.nextInt();
    		Example x = new Example();
    		x.getPatternDisplay(k);
    	}
     
    	public void getPatternDisplay(int k) {
     
    		for (int i = 1; i < k; i += 2) {
    			for (int j = 0; j < k - i / 2; j++)
    				System.out.print(" ");
    			for (int j = 0; j < i; j++)
    				System.out.print("*");
    			System.out.println();
    		}
     
    		for (int i = k; i > 0; i -= 2) {
    			for (int j = 0; j < k - i / 2; j++)
    				System.out.print(" ");
    			for (int j = 0; j < i; j++)
    				System.out.print("*");
    			System.out.println();
    		}
    	}
    }
    Whatever you are, be a good one

  12. #12
    Super Moderator Norm's Avatar
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    Default Re: Display patterns using loops

    Yes, something like that. The variable name k is a bit obscure: k??? instead of nbrOfRows that describes what is in it.
    If you don't understand my answer, don't ignore it, ask a question.

  13. The Following User Says Thank You to Norm For This Useful Post:

    John Joe (January 18th, 2018)

  14. #13
    Member John Joe's Avatar
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    Default Re: Display patterns using loops

    Thanks, I will aware of the variables used next time
    Whatever you are, be a good one

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