positioning objects from a text file

Question

Working with C# I have written the position of my game objects to a text file each frame, giving me a file looking like this

P,130,140,B,200,300,B,400,600-P,131,140,B,201,300,B,401,600-

above shows two frames and 3 objects positions adding 1 to each X coordinate on the second frame.

The P is for the player object and then the X and Y coordinate, then two Ball objects with their X and Y coordinates.

I am looking to replay saved gameplay by assigning positions of objects each frame as it reads through the file. Using a letter to determine the next visible object and the - to determine the end of the frame

I can't get my head around the syntax to read through the file, I was thinking something on the lines of

While (text != "-")
{ if (text = "P") Create Object player
player.X = nextText; player.Y = nextText;
if (text = "B") Create Object Ball
Ball.X = nextText; Ball.Y = nextText;
}

the nextText variable is to indicate I'm after the next bit of the text file after the comma , I am not sure how to work with multiple text delimiters. Any help would be greatly appreciated.

Answer 1

 static class Program
{
    static void Main(string[] args)
    {
        using (StreamReader sr = new StreamReader(@"D:\1.txt"))
        { 
            String s = null;
            while ((s = sr.ReadUntil('-')) != null)
            {
                if (s.StartsWith("P"))
                { 

                    //crate object
                }
                if (s.StartsWith("B"))
                {

                    //..
                }
            }
        }
    }

    public static String ReadUntil(this StreamReader reader, char delimeter)
    {
        StringBuilder sb = new StringBuilder();
        char c;
        while ((c = (char)reader.Read()) != 0)
        {
            if (c == delimeter)
                return sb.ToString();
            else
                sb.Append(c);
        }

        return sb.Length == 0 ? null:sb.ToString();

    }
}

Answer 2

By far the easiest way for you is to first Split() your string on "-" character, to get an array of frames and then use a simple regex to split P, B and B objects. Something like this:

string WholeFile = System.IO.File.ReadAllText("YOUR PATH HERE");
var Frames[] = WholeFile.Split('-');

    Regex rx = new Regex(@"P,(?<Px>\d+),(?<Py>\d+),B,(?<B1x>\d+),(?<B1y>\d+),B,(?<B2x>\d+),(?<B2y>\d+)", RegexOptions.ExplicitCapture | );

foreach(var frame in Frames)
{
    var Captures = rx.Match(frame);

    //now use Captures.Groups["Px"] etc. to get your values
}