How can I parse integer from a user provided string

Question

I have a specification where the user needs to type in a string of pair of co-ordinates like:

{{2,3}, {9,0}}

these are the co-ordinates of a line on a 2-D axis.

I want to parse this user-input string during runtime dynamically in C# and enter these co-ordinates in a 2-D array. I know we can do hard-coded:

int[,] CoOrdinates = {{2,3}, {9,0}};

but I do not know how to get the user to type in a string and get the co-ordinates from the string to store in the array dynamically.

I'm using Console.Readline(); to get the user to input the co-ordinates.

Please help, thanks!

you probably want to use the System.Drawing.Point struct, it is basically x,y pairs — Neil N
– Neil N, Commented Jun 23, 2011 at 12:47
@Oded, as strings are arrays, I tried to pick up characters from their positions as: 'string inputCoOds = Console.ReadLine(); int CoOd1X = int.Parse(inputCoOds[2].ToString()); int CoOd1Y = int.Parse(inputCoOds[4].ToString());` This is a bit ugly and non-generic, so I wanted a more elegant solution. — dhrumilap
– dhrumilap, Commented Jun 25, 2011 at 5:25

Kongress · Accepted Answer · 2011-06-23 12:49:15Z

1

I would use a regular expression (Regex class in C#) to parse out the bits of the string you want, and then Int32.TryParse() to convert the string to a number. This is a good resource for constructing regular expressions, and this is my preferred regex tester. Good luck.

answered Jun 23, 2011 at 12:49

Kongress

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2 Comments

Daniel A. White Over a year ago

I would use TryParse instead.

Kongress Over a year ago

@Daniel Agreed, TryParse is preferable.

Dummy01 · Accepted Answer · 2011-06-23 13:00:20Z

0

A quick answer:

    public void IntegerReader()
    {
        string integers = Console.ReadLine();

        string[] split = integers.Split(',');

        int result;

        foreach (string s in split)
        {
            if (!string.IsNullOrEmpty(s.Trim()))
                if (int.TryParse(s.Trim(), out result))
                    Console.WriteLine(result);
        }
    }

answered Jun 23, 2011 at 13:00

Dummy01

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3 Comments

Dummy01 Over a year ago

@jlafay Did you tried in an Console Application? Because otherwise, yes it will give an exception because integers gets its value from Console.ReadLine()

Jeff LaFay Over a year ago

I tried a string with the prescribed coordinate format that the OP specified. Did you try it? I think that maybe your split doesn't work.

Dummy01 Over a year ago

As I said in my answer, I just gave a quick one using comma as a separator. Just to let him get an idea. He can change the separators list in Split menthod to include all the ones he want.

Jeff LaFay · Accepted Answer · 2011-06-23 13:18:12Z

This isn't super elegant but I think the result is what you expect

string coords = "{{2,3}, {9,0}}";
string matchPattern = @"\{\{(?<x1>\d{1})\,(?<y1>\d{1})\}\,\s*\{(?<x2>\d{1})\,(?<y2>\d{1})\}\}";

var matches = Regex.Match(coords, matchPattern);

int[,] values = new int[2,2];

int.TryParse(matches.Groups["x1"].ToString(), out values[0,0]);
int.TryParse(matches.Groups["y1"].ToString(), out values[0,1]);

int.TryParse(matches.Groups["x2"].ToString(), out values[1,0]);
int.TryParse(matches.Groups["y2"].ToString(), out values[1,1]);

/* Result:
 *    0  1
 *   -----
 * 0| 2  3
 * 1| 9  0
 */

Of course you will want to check that four groups were returned before assigning values to the rectangular array, but that should be easy enough for you to implement.

hungryMind · Accepted Answer · 2011-06-23 13:46:44Z

0

            string s = "{{2,3}, {9,0}}";
            string p = "{(?<x>\\d),(?<y>\\d)}";
            Regex regex = new Regex(p);
            MatchCollection ms = regex.Matches(s);
            int[,] cood = new int[ms.Count, ms.Count];
            int i =0;
            foreach (Match m in ms)
            {
                cood[i,0] = int.Parse(m.Groups["x"].Value);
                cood[i, 1] = int.Parse(m.Groups["y"].Value);
                i++;
            }

You can use TryParse if wrong value in coordinates is expected

edited Jun 23, 2011 at 13:46

answered Jun 23, 2011 at 12:59

hungryMind

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