C＃使用带有二维数组的输入坐标打印“ *”字符

Question

I have been trying to do a task I recieved a few days earlier. Basically the task is a console application in C# :

Prompt the user for input of 2 coordinates in untill the word "stop" is entered. Once the word "stop" is hit, print a "*"(star char) at each of the input coordinates. The field where the coordinates are printed is 20x20. I have tried doing this, but to no avail. If somebody could help me out and show me how to store the input x,y into a 2d array, that'd be great :)

How the application should work : http://imgur.com/a/SnC1k

The [0,5] [18,18]etc are the entered coordinates which are later on printed down below. The "#" chars dont need to be printed , they are here only to help with the understanding of the task.

How I tried to do it but DIDN'T work :

namespace ConsoleApplication1
{   
class Program
{
    static void Main(string[] args)
    {
        bool stopped = false;
        int x=0;
        int y=0;


        while (stopped)
        {
            string[,] coordinates = Console.ReadLine();
            string response = Console.ReadLine();
            response = response.ToLower();

            if (response == "STOP")
                stopped = true;
            else
            {
                string[] xy = coordinates.Split(',');
                x = int.Parse(xy[0]);
                y = int.Parse(xy[1]);

                Console.SetCursorPosition(x, y);
                Console.Write("*");
            }






        }


    }
    }
    }

The code I did just doesn't do it. It shows multiple errors that I do not know how to fix and the only thing I was able to do is get it to print a char immediately when I enter the first coordinates, instead of printing a char at every entered coordinate, AFTER the word STOP is hit.

Answer 1

Create a 20x20 2d array. Prompt the user for the x and y. Once you have each store a 1 in your array[x,y] once the user hits stop loop through the array and print '#' if null or 0 and print '*' if its a 1.

Edit, something along these lines I didn't check if this works or compiles but should get you on the right track.

    int[,] grid = new int[20,20];
    while (!stopped)
    {
        string[,] coordinates = Console.ReadLine();
        string response = Console.ReadLine();
        response = response.ToUpper();

        if (response == "STOP")
            stopped = true;
        else
        {
            string[] xy = coordinates.Split(',');
            x = int.Parse(xy[0]);
            y = int.Parse(xy[1]);
            grid[x,y] = 1;  
        }

        for (int i = 0; i < 20; i++)
        {
            for (int j = 0; j < 20; j++)
            {
                if (grid[i, j] > 0)
                    Console.Write("*");
                else
                    Console.Write("#");
            }
            Console.WriteLine("");
        }
    }

Answer 2

As you only need to display a matrix-style output you don't need to use Console.SetCursorPosition(x, y);

Also you should read the user input somehow and set the proper value for the given position instead of store the coordinates.

Try this and let me know how this works for you. You can see it also on this fiddle. Enter the coordinates as two space-separated numbers and enter stop to print.

using System;

public class Program
{
    public static void Main(string[] args)
    {
        int x=0;
        int y=0;
        char[,] coordinates = new char[20,20];

        while (true)
        {
            //user must enter 2 3 for example.
            string[] response = Console.ReadLine().Split(new[]{" "}, StringSplitOptions.RemoveEmptyEntries);
            if (response[0].ToLower() == "stop")
                break;

            x = int.Parse(response[0]);
            y = int.Parse(response[1]);

            coordinates[x,y] = '*';
        }


        //Print the output
        for(var i = 0; i < 20; i++)
        {
            for( var j = 0; j < 20; j++)
                if (coordinates[i,j] == (char)0)
                    Console.Write('#');
                else 
                    Console.Write(coordinates[i,j]);

            Console.WriteLine();
        }
    }
}

Hope this helps!

Answer 3

I suggest decomposing the task, cramming entire rountine into a single Main as bad practice; you should:

- ask user to enter coordinates
- print out the map

Let's extract the methods:

private static List<Tuple<int, int>> s_Points = new List<Tuple<int, int>>();

private static void UserInput() {
  while (true) {
    string input = Console.ReadLine().Trim(); // be nice, let " stop   " be accepted

    if (string.Equals(input, "stop", StringComparison.OrdinalIgnoreCase))
      return;

    // let be nice to user: allow he/she to enter a point as 1,2 or 3   4 or 5 ; 7 etc.
    string[] xy = input.Split(new char[] { ',', ' ', ';', '\t' },
                              StringSplitOptions.RemoveEmptyEntries);
    int x = 0, y = 0;

    if (xy.Length == 2 && int.TryParse(xy[0], out x) && int.TryParse(xy[1], out y)) 
      s_Points.Add(new Tuple<int, int>(x, y));
    else
      Console.WriteLine($"{input} is not a valid 2D point.");
  }
}

Printing out

private static void PrintMap(int size = 20) {
  // initial empty map; I prefer using Linq for that, 
  // you can well rewrite it with good old for loops
  char[][] map = Enumerable.Range(0, size)
    .Select(i => Enumerable.Range(0, size)
       .Select(j => '#')
       .ToArray())
    .ToArray();

  // fill map with points; 
  // please, notice that we must not print points like (-1;3) or (4;100) 
  foreach (var point in s_Points)
    if (point.Item1 >= 0 && point.Item1 < map.Length &&
        point.Item2 >= 0 && point.Item2 < map[point.Item1].Length)
      map[point.Item1][point.Item2] = '*';

  // The string we want to output; 
  // once again, I prefer Linq solution, but for loop are nice as well
  string report = string.Join(Environment.NewLine, map
    .Select(line => string.Concat(line)));

  Console.Write(report);
}

Finally, all you have to do it to call the methods:

static void Main(string[] args) {
  UserInput(); 
  PrintMap();

  Console.ReadKey();
}