Enumerable.Concat not working

Question

Below is the code:

string[] values = Acode.Split(\',\');
IEnumerable tst = null;

foreach (string a in values)
{
    if (tst== null)
        tst          


        

Answer 1

That is because Concat will return a new instance of your enumerable.

Either use in your else :

tst = tst.Concat(...)

Or Change your Enumerable into list from the beginning :

string[] values = Acode.Split(',');
List tst= new List;

foreach (string a in values)
{
    tst.AddRange(entities.Test.Where(g => (g.TCode == Convert.ToInt16(a))));
}

return tst;