Read integer input and print a matrix

Question

I am trying to write a program that reads from the console a positive integer N (N < 20) and prints a matrix like these ones:

This is my code:

using System;
namespace _6._12.Matrix
{
    class Program
    {
        static void Main()
        {
            Console.WriteLine("Please enter N ( N < 20): ");
            int N = int.Parse(Console.ReadLine());
            int row;
            int col;
            for (row = 1; row <= N; row++)
            {
                for (col = row; col <= row + N - 1; )
                {
                    Console.Write(col + " ");
                    col++;
                }
                Console.WriteLine(row);
            }
            Console.WriteLine();
        }
    }
}

The problem is that the console prints one extra column with the number from 1 to N and I dont know how to get rid of it. I have an idea why this might be happening but still can't find a solution.

First check whether N<20 or else again ask user to put a number < 20 — Nikhil Agrawal
– Nikhil Agrawal, Commented Aug 6, 2012 at 6:14

Fredou · Accepted Answer · 2012-08-06 06:34:46Z

4

simple, change Console.WriteLine(row); for Console.WriteLine();

while your at it;

    static void Main()
    {
        int N;

        do
        {
            Console.Write("Please enter N (N >= 20 || N <= 0): ");
        }
        while (!int.TryParse(Console.ReadLine(), out N) || N >= 20 || N <= 0);

        for (int row = 1; row <= N; row++)
        {
            for (int col = row; col <= row + N - 1; )
            {

                Console.Write(col + " ");
                col++;
            }
            Console.WriteLine();
        } 

        Console.Read();
    }

Please enter N (N >= 20 || N <= 0): 5
1 2 3 4 5 
2 3 4 5 6 
3 4 5 6 7 
4 5 6 7 8 
5 6 7 8 9

edited Aug 6, 2012 at 6:34

answered Aug 6, 2012 at 6:20

Fredou

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2 Comments

Bezideiko Over a year ago

Okey. The extra column disapear, but now a number: N + 1 appear bellow the first column which is not needed.

Fredou Over a year ago

@AngelElenkov, can you tell me where?

daryal · Accepted Answer · 2012-08-06 06:22:14Z

1

Just change this line Console.WriteLine(row); to this Console.WriteLine(); The problem here is that; at the end of each inner loop, you are writing the row value again; which is not needed.

answered Aug 6, 2012 at 6:22

daryal

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Comments

user204492 · Accepted Answer · 2012-08-06 06:34:21Z

0

The first question is what do you think Console.WriteLine(row) is doing? It is critical, when you are learning to program, to 'see' what the code is doing and why it is doing it, rather than running it, tweaking it, and then running it again to see if it acts the way you want it to. Once you see, in your head, clearly and concisely what the code is doing, you will notice that the Console.WriteLine(row) is not right and that you just need to write a newline at that point.

answered Aug 6, 2012 at 6:34

user204492

Comments

johnnyRose · Accepted Answer · 2016-03-01 01:37:11Z

0

Here is another approach using an if statement instead of using a do while, the code looks a little simpler:

 static void Main(string[] args)
 {
     Console.Write("Give a number from 1 to 20: ");
     int n = int.Parse(Console.ReadLine());
     int row,col;
     Console.WriteLine("");
     if (n > 0 && n < 21)
     {
         for (row = 1; row <= n; row++)
         {
             for (col = row; col <= row + n - 1;col++ )
             {
                 Console.Write(col + " ");
             }

             Console.WriteLine();
         }
     }
     else
     {
         Console.WriteLine("This number is greater than 20 or smaller than 1");
     }
 }

edited Mar 1, 2016 at 1:37

johnnyRose

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answered Mar 1, 2016 at 1:33

Kujtim

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Comments

Imtiaz Afridi · Accepted Answer · 2018-09-06 06:31:41Z

0

// All the above answer i tired are wrong u should once try this and then reply me...

        Console.Write("Enter N: (N < 20) ");
        int n = Int32.Parse(Console.ReadLine());

        for (int row = 1; row <= n;row++)
        {
            Console.Write(row+" ");
            for (int col = row+1; col <= row + n - 1; )
            {
                Console.Write(col + " ");
                col++;
            }
            Console.WriteLine();

        }
        Console.ReadLine();

answered Sep 6, 2018 at 6:31

Imtiaz Afridi

1

Comments

Lasitha Yapa · Accepted Answer · 2020-06-11 12:25:42Z

-1

using System;
namespace _6._12.Matrix
{
    class Program
    {
        static void Main()
        {
            Console.WriteLine("Please enter N ( N < 20): ");
            int N = int.Parse(Console.ReadLine());
            int row;
            int col;
            for (row = 1; row <= N; row++)
            {
                for (col = row; col <= row + N - 1; )
                {
                    Console.Write(col + " ");
                    col++;
                }
                Console.WriteLine(row);
            }
            Console.WriteLine();
        }
    }

edited Jun 11, 2020 at 12:25

Lasitha Yapa

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answered Jun 11, 2020 at 11:56

user13727454

1

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