Print right angle triangle with characters

Question

I want to create a right angled triangle made out of characters. The code asks you how many rows you want the triangle to be, and the maximum is 26 of course. When I test the code I input 5 (for no reason). This is my code so far:

import java.util.*;

public class Uppgift3 {
    public static void main (String [] args) {

        Scanner input = new Scanner (System.in);

        System.out.print("Ange längden på de 2 lika långa sidorna (avsluta med -1): ");
        int rader = input.nextInt();

        int i = 0;
        int j = 0;
        int k = 0;
        char bokstav = (char)( i + 'A');

        for (i=0; i<rader; i++) {
            for (j=0; j<i+1; j++) {
                System.out.print(bokstav);

            }bokstav++;
            System.out.println();

        }

    }

}

This is the output I am after (if you input 5):

A
AB
ABC
ABCD
ABCDE

This is what I get when I input 5 in the code above:

A
BB
CCC
DDDD
EEEEE

Can someone please help me? Am I on the right track, or am I completely lost? Feels like the latter... And yes, this is for school. I have tried as much as I can, and I am now stuck.

Much appreciated!

Change `}bokstav++;` to `bokstav++; } bokstav = 'A';`. Or change your loop to `for (int i = 1; i <= rader; i++) { for (int j = 0; j < i; j++) System.out.print((char)('A' + j)); System.out.println(); }`. Or `for (int i = 1; i <= rader; i++) System.out.println("ABCDEFGHIJKLMNOPQRSTUVWXYZ".substring(0, i));`. — shmosel, Feb 09 '18 at 02:25

score 0 · Answer 1 · answered Feb 09 '18 at 02:31

You were not incrementing your bokstav variable in the right place. Also you would need to reset it per row.

Try this:

public static void main (String [] args)
{

    Scanner input = new Scanner (System.in);

    System.out.print("Enter the amount of rows your want: ");
    int rows = input.nextInt();

    char bokstav = 'A';

    for(int i=0; i<rows; i++)
    {
        for(int j=0; j<i+1; j++)
        {
            System.out.print(bokstav);
            bokstav++;
        }

        bokstav = 'A';
        System.out.println();

    }

}

score 0 · Accepted Answer · answered Feb 09 '18 at 03:20

The problem with your solution is that you only increment the character after each line is written; You should be incrementing the character after each character is written. Upon a successful line write, you should reset the character to 'A'.

    for (int i = 0; i < 5; i++) {
        char c = 'A';
        for (int j = 0; j < i+1; j++) {
            System.out.print(c);
            c++;
        }
        System.out.println();
    }

I will also point out that this solution is not recursion. A simple definition of recursive method is one that will call itself to find the solution to smaller segments of the problem. For example, a recursive solution to printing a similar pyramid make look something like this.

public static void print(int level) {
    if (level <= 0 || level > 26) {
        return;
    }
    print(level - 1);
    System.out.println(line(level));
}

public static String line(int level) {
    String line = "";
    if (level > 0 && level <= 26) {
        line = line(level--) + (char)('A' + level);
    }
    return line;
}

Okay! I have changed the title. Thank you for pointing that out! — Adam Rana, Feb 09 '18 at 15:30

score -1 · Answer 3 · answered Feb 09 '18 at 02:29

-1

Try this:

char bokstav = 'A';

for (i=0; i<rader; i++) {
    bokstav = 'A';
    for (j=0; j<i+1; j++) {
        System.out.print(bokstav++);
    }
    System.out.println();
}

answered Feb 09 '18 at 02:29

E. Betanzos

1,312
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Please don't post "try this" code-dump answers. At least *explain* the answer since the explanation is more important than the posted code. – Hovercraft Full Of Eels Feb 10 '18 at 14:05

Print right angle triangle with characters

3 Answers3