Print out a triangle by character *

I need a triangle like this

Code Java:

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

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I just know how to print like this :

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

Can you guys give me some hints. Thank you very much.
My code is:

Code Java:

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	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		System.out.print("Enter your number: ");
		int n = s.nextInt();
		for (int i = 0; i < n; i++) {	
			for (int j = 0; j < n; j++) {
				System.out.print("*");
			}
			System.out.println();
		}
	}

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Does this mean you have to input an odd number?

You would have to print spaces on every line except the last line. How many spaces on the first line? How many on the second? You can get this value with some math and an index variable from one of the loops.

Plan out what you have to make happen and then write the code to do it.

Quote:

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Originally Posted by Genky

I need a triangle like this

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

---

...code removed by moderator

Please don't spoonfeed code. Read this:
http://www.javaprogrammingforums.com...n-feeding.html

I mean I was required to show a isoceles triangle. But I don't know how to edit it in above post.

What is the pattern of what is printed on each line?
Take a piece of paper and draw on it the spaces and *s that you want to print.
What prints on the first line? X spaces and one *
What prints on the 2nd line? Y spaces, one *, Z space(s), one *
Continue writing what goes on the next 3-4 lines.
Now look at the number of leading spaces (X and Y above) and the number of inside spaces (Z) for the lines
and see how they are related to the location of the line.

I saw there are 4 lines. Each line the number of spaces decrease by one, and the number of * increase 1,3,5,7.

Can you compute the number of *s from the number of the line? Or another way would be to use a counter for the number of *s. Start at 1 and increase by 2 for each line.
Look at using loops, one to print the spaces and one to print the *

Code Java:

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                               for (int i = 0; i <4; i++) {
				System.out.printf("%" + i + "s", "");
				for (int j = 0; j < 4; j++) {
					System.out.print("*");
				}
				System.out.println();
			}

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But I don't know how to print spaces. Why do I feel it's so hard X_X.

Quote:

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how to print spaces

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A space is just another character. Put it inside of some "s:
" " for a space
vs
"*" for an *

You mean like this

Code :

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                          for (int i = 0; i <4; i++) {
				System.out.print(" ");
				for (int j = 0; j < 4; j++) {
					System.out.print("*");
				}
				System.out.println();
			}

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But it just print:
****
****
****
****

Look at the steps in the algorithm you worked out for the code and get that right first.
Then write the code. Your code obviously doesn't follow the right algorithm.
Can you post the algorithm's steps so we can see how it is supposed to work?

-The first line it prints one *, spaces = number row - number of *
- Each line decrease number of * by 2.

Not a good algorithm.

Quote:

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The first line it prints one *

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I thought there were spaces before the * on the first line? You steps say to print an * first.

Quote:

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Each line decrease number of * by 2.

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If you start with 1 and decrease by 2 there are negative numbers.
What about the leading spaces on each line before the *s?

Quote:

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Originally Posted by Norm

Not a good algorithm.

I thought there were spaces before the * on the first line? You steps say to print an * first.

If you start with 1 and decrease by 2 there are negative numbers.
What about the leading spaces on each line before the *s?

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You're so patient.


The first line has 3 spaces, one *
The second line has 2 spaces, three ***
The second line has 1 spaces, five *****
The second line has 0 spaces, three *******

So, We have to print 4 row,spaces start each row -1, each increase number of * = 2.

write an expression using the line number to compute the number of spaces
and another expression to compute the number of *s on a line
The pseudo code could be:

Quote:

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init variables
begin loop1 for number of lines to print
compute number of spaces for this line
print the spaces
compute the number of *s for this line
print the *s
move to next line
end loop1

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Quote:

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Originally Posted by Norm

write an expression using the line number to compute the number of spaces
and another expression to compute the number of *s on a line
The pseudo code could be:

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Code Java:

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	int n = 4;
		for(int i =0; i<n;i++){
			int space = n-1;
			System.out.printf("%",spa," ");//want to print number of spaces
				int numsta =i+2;//but it's not true
				for (int j = 0; j < numsta; j++) {
					System.out.print("*");
				}
				System.out.println();
		}

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Does the code work? Does it compile, execute and produce the desired results?

Think this way,

int j=10;
for(int i=1 ; i<10 ; i= i+2) {
...
}

i will give you *,
j-i will give you white space

Quote:

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Originally Posted by Norm

Does the code work? Does it compile, execute and produce the desired results?

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It didn't run in this line System.out.printf("%",spa," "); . Can you correct for me?
And int numsta =i+2 does not bring correct result.

Quote:

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It didn't run in this line

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If you get a compiler error, please copy and paste the full text of the error message here. Otherwise explain what you mean by "it didn't run".

Quote:

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And int numsta =i+2 does not bring correct result.

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Please explain what the problem is. Show the results that the program generates and explain what is wrong with it.

Quote:

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Originally Posted by Norm

If you get a compiler error, please copy and paste the full text of the error message here. Otherwise explain what you mean by "it didn't run".

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I searched and wrote code for print space like this:

String space = String.format("%" + (n-1) + "s"," ");

But it just prints 4 space. I don't know why.


Please explain what the problem is. Show the results that the program generates and explain what is wrong with it.

I increase each line print *+2 but it wasn't true.

Quote:

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I increase each line print *+2 but it wasn't true.

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Can you show the programs output and explain what the problem is.

I don't understand what your question is. What is *+2?

Quote:

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But it just prints 4 space. I don't know why.

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Does the value of n change? If it doesn't change then the printf() method call will print the same thing every time.

Quote:

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Originally Posted by Norm

Can you show the programs output and explain what the problem is.

I don't understand what your question is. What is *+2?


Does the value of n change? If it doesn't change then the printf() method call will print the same thing every time.

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This is the out put:

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

The problems is : The space doesn't show correct.

I mean I've increased number of * each time in for loop = * + 2*.

Code Java:

---

	int n = 4;
		for(int i =0; i<n;i++){
			String space = String.format("%" + (n-1) + "s"," ");
			System.out.printf(space);
			int numsta = i+2;
				for (int j = 0; j < numsta; j++) {
					System.out.print("*");
				}
				System.out.println();
		}

---

Quote:

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The space doesn't show correct.

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Please explain what is wrong with the spaces.

Quote:

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increased number of * each time in for loop = * + 2*.

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Does that give you the right output?