LINQ Select返回Null

Question

I am reading a csv file and placing it in this structure:

List<Dictionary<string, object>> l = new List<Dictionary<string, object>>();

The CSV File contains:

cod_curso; name
3; language
5; math
6; physic

The code I have to do this is:

    string path = "test.csv";
    List<Dictionary<string, object>> l = new List<Dictionary<string, object>>();

    using (var reader = new StreamReader(path))
    {
        var header = reader.ReadLine();
        var keys = header.Split(";");

        while (!reader.EndOfStream)
        {
            var line = reader.ReadLine();
            var values = line.Split(';');

            for (int i = 0; i < values.Length; i++)
            {
                Dictionary<string, object> d = new Dictionary<string, object>();
                d.Add(keys[i], values[i]);
                l.Add(d);
            }
        }
    }

To go through the structure I use the following:

foreach (var item in l)
{
   foreach (var dic in item)
   {
      Console.WriteLine(dic.Key + " " + dic.Value);
   }
}

What I'm trying to do is select the values of the dictionary by key, but it does not work for me, by doing:

var b = l.Select(a => a["cod_curso"]);

I get null.

"cod_curso" is a column of the csv file and is as a key in the dictionary

The next image is what I get in the debug

How could I achieve what I am looking for? Or why does this happen?

Answer 1

You want each dictionary to be created and added outside the inner loop, like:

    while (!reader.EndOfStream)
    {
        var line = reader.ReadLine();
        var values = line.Split(';');
        var d = new Dictionary<string, object>(); // New dictionary for each line

        for (int i = 0; i < values.Length; i++)
        {
            d.Add(keys[i], values[i]);
        }

        l.Add(d);
    }