Question

I am using List<T> array to store all ID’s that I have read from my database file.

do lets say I have ID: 5, 8, 15

What I am trying to do is to check if user input matches one of the elements in this array.

How do I do this?

I have tried using Contains or Find, but I cannot manage to make it work.

Bit of the code which doesn’t seem to wok. It only shows Entry ID doesn't exist! only if I enter a letter (?).

    List<int> fetchedEntries = new List<int>();

    else if (!fetchedEntries.Contains(intNumber))
    {
        lblMessage.Text = "Entry ID doesn't exist!";
        lblMessage.ForeColor = Color.IndianRed;
        btnDeleteEntry.Enabled = false;
    }

Answer 1

The easiest way is to use the Contains method

List<int> theList = GetListFromDatabase();
if (theList.Contains(theNumber)) {
  // It's in the list
}

Your Q said this isn’t working for you though. Could you give some more information? The above pattern should work just fine