Question

I try to get first character occurrence in text keeping their original order. I try to use LINQ but I’m very new in this, so something is wrong, and I have bad result.

For example I write: “languages”, so the result would l-0, a-1, n-2, g-3, u-4, e-7, s-8 (digit mean index of occurrence). But my code gives: l-0, a-1, n-2, g-3, u-4, e-5, s-6.

So index number is 0,1,2,3,4,5 no matter what. That’s my code:

char[] result = text.ToLower()
    .Where(char.IsLetter)
    .GroupBy(x => x)
    .Select(g => g.Key).ToArray();

for (int i = 0; i < result.Length; i++)
{
    listView1.Items.Add(result[i].ToString());
    listView1.Items[i].SubItems.Add(i.ToString());
}

Answer 1

I would use Regex:

using System.Text.RegularExpressions;

var q = from ch in text.Distinct()
        select Regex.Match(text, ch.ToString());
foreach (var item in q)
{
    Console.WriteLine("{0}-{1}", item.Value, item.Index);
}

And a non-regex alternative:

var q = from ch in text.Distinct()
        select new { Value = ch, Index = text.IndexOf(ch) };