Reading CSV file, match column 3 to column 1 on separate lines

Question

I am beating my head against the wall, and I'm hoping that someone can point me in the right direction. This can't be as complicated as I'm making it.

I'm working on a project where the program reads one file (that's approx 50 lines or so) and I need to have it match data on the third column to data on the first column of a separate line. I opened up a new project because it was getting too complex for such an easy task.

Here's an example file that is closely relevant to the actual file I'm working with:



a1,b1,c1,d1

**c4**,b2,c2,d2

a3,b3,c3,d3

a4,b4,**c4**,d4

a5,b5,c4,d5

I promise this isn't for a school project, this is something that I need to figure out for work purposes.

Here is what I have, and I know it's just not going to work because it's only reading line by line for comparison. How do I get the program to read the current array value in the foreach command against the entire file that I caught in streamreader?

    static void Main(string[] args)

    {

        StreamReader sr = new StreamReader("directories.txt");

        string sline = sr.ReadLine();

        string[] sarray = sline.Split(',');

        string col3 = sarray[2];

        string col1 = sarray[0];

        foreach(string a in sarray)

        {

            // ?!?!?!!!

            // I know this won't work because I'm comparing the same line being read.

            // How in the world can I make this program read col3 of the current line being read against the entire file that was read earlier? 

            if (col3 == col1)

            { 

                Directory.CreateDirectory("DRIVE:\\Location\\" + a.ToString());

            }



        }

    }

Thank you ahead of time!

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Answer 1

Since your file is small you can go with the simplest path...

var lines = File.ReadLines(filename)
            .Select(line => line.Split(','))
            .ToList();

var result = from a in lines
             from b in lines
             where a[0] == b[2]
             select new { a, b };

foreach(var x in result)
{
    Console.WriteLine(string.Join(",", x.a) + " - " + string.Join(",", x.b));
}

Reading CSV file, match column 3 to column 1 on separate lines

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