如何从列表添加项目 <T> 进入组合框，但在C＃中不重复

Question

In a WPF project I have a simple List called "items" containing the following:

EURUSD
EURUSD
NZDUSD

I want to populate a comboBox with unique instances of the above. So I wrote a foreach loop to go through the "items" members, and then a for loop to check whether a given member was already present within the combobox (so not to add duplicates). My code is:

private void Test(object sender, EventArgs e)
{
    comboBox.Items.Clear();
    foreach (var positionz in items)
    {

        if (items.Count == 0) return;
        int combocount = comboBox.Items.Count;
        if (combocount == 0)
        {
            comboBox.Items.Add(positionz.Symbol);
            continue;
        }
        for (int i = 0; i < combocount; i++)
        {

            if (comboBox.Items[i].ToString() == positionz.Symbol)
            {
               label.Content=i + "Good "  + positionz.Symbol + " matches combo item " + comboBox.Items[i].ToString();
                continue;
            }
            else { comboBox.Items.Add(positionz.Symbol); }
            label_Copy.Content = i;
        }

    }
}

The label stuff is just me trying to catch at what point the mistake is. For same reason when it matches the duplicate and continues to the next "i", it still adds the symbol to the combobox.

I'm sure I'm overlooking something silly but I can't figure it out.

Answer 1

Leaving aside data binding and possible equality issues... using System.Linq; you could replace the complete foreach with just:

foreach (var symbol in items.Select(i => i.Symbol).Distinct())
{
    combobox.Items.Add(symbol);
}