string sorting in C#

Question

I have an array of strings like the following:

"access"
"Addition"
"account"
"base"
"Brick"
"zammer"
"Zilon"

I want them to sort them witht the following rules"

Capital letters for a given character should come first.
The capital and small letters should be sorted in their own groups.

Thus, the output should be:

"Addition"
"access"
"account"
"Brick"
"base"
"Zilon"
"zammer"

The language I am using is C# and .Net 4.0.

score 7 · Answer 1 · answered Feb 25 '14 at 05:33

7

Proper set of OrderBy/ThenBy calls will do the trick.

Order by first letter lowercased, to get all as and As first, then bs and Bs, etc.
Then by IsLower(firstCharacter), which will get the uppercased items for each letter first.
Then by the entire string.

var sorted = source.OrderBy(s => char.ToLower(s[0]))
                   .ThenBy(s => char.IsLower(s[0]))
                   .ThenBy(s => s)
                   .ToList();

answered Feb 25 '14 at 05:33

MarcinJuraszek

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It might be nicer to be: `source.OrderBy(s => char.ToLower(s[0])).ThenByDescending(s => s)`. That seems to do the job. +1 anyway. – Simon Whitehead Feb 25 '14 at 05:36
+1, but won't that only work if there are no caps in the middle of the string? (granted, there aren't any in the OP's example but the stated requirements don't preclude this possibility). – Baldrick Feb 25 '14 at 05:37
1

@Baldrick Yes, I assumed the upper/lower rule works only for first character. – MarcinJuraszek Feb 25 '14 at 05:38
@MarcinJuraszek: Hmm.. would be nice to get a more general solution.. but probably just perfect for OP's problem! Nice work. – Baldrick Feb 25 '14 at 05:39
The strings can very well contain caps in between. – James Feb 25 '14 at 05:46
I appreciate the answer but I have to handle the "caps in between" case also. – James Feb 25 '14 at 07:01
You should update your sample input/output to match that requirement. – MarcinJuraszek Feb 25 '14 at 07:02

score 0 · Answer 2 · answered Feb 25 '14 at 05:31

Try like this

List<string> list = new List<string>();
list.Add("access");
list.Add("Addition");
list.Add("account");
list.Add("base")
list.Add("Brick")
list.Add("zammer")
list.Add("Zilon")
list = list.Where(r => char.IsLower(r[0])).OrderBy(r => r)
      .Concat(list.Where(r => char.IsUpper(r[0])).OrderBy(r => r)).ToList();
for (int i = 0; i < list.Count; i++)
    Console.WriteLine(list[i]);

score 0 · Answer 3 · answered Feb 25 '14 at 07:02

Below solution works for more than one Caps.

   static void Main(string[] args)
    {

        var names = new List<String>() {
        "access",
        "Addition",
        "ADDition",
        "ADdition",
        "account",
         "base",
        "Brick",
        "zammer",
        "Zilon"
        };


        names.Sort((one, two) =>
        {
            int result = 0;

            var oneArray = one.ToCharArray();
            var twoArray = two.ToCharArray();

            var minLength = Math.Min(oneArray.Length, twoArray.Length) - 1;
            var i = 0;

            while (i < minLength)
            {
                //Diff Letter
                if (Char.ToUpper(one[i]) != Char.ToUpper(two[i]))
                {
                    result = Char.ToUpper(one[i]) - Char.ToUpper(two[i]);
                    break;
                }

                // Same Letter, same case
                if (oneArray[i] == twoArray[i])
                {
                    i++;
                    continue;
                }
                // Same Letter, diff case
                result =  one[i] - two[i];
                break;
            }

            return result;
        });

        foreach (string s in names)
            Console.WriteLine(s);

        Console.WriteLine("done");

score 0 · Answer 4 · answered Feb 25 '14 at 12:15

If you want to go beyond the first character, I should implement a comparer:

class MyComparer : IComparer<string>
{
    public int Compare(string x, string y)
    {
        if ((x == null) && (y == null))
        {
            return 0;
        }

        if (x == null)
        {
            return 1;
        }

        if (y == null)
        {
            return -1;
        }

        var l = Math.Min(x.Length, y.Length);
        for (var i = 0; i < l; i++)
        {
            var c = x[i];
            var d = y[i];
            if (c != d)
            {
                if (char.ToLowerInvariant(c) == char.ToLowerInvariant(d))
                {
                    return StringComparer.Ordinal.Compare(new string(c, 1), new string(d, 1));
                }
                else
                {
                    return StringComparer.OrdinalIgnoreCase.Compare(new string(c, 1), new string(d, 1));
                }
            }
        }

        return x.Length == y.Length ? 0 : x.Length > y.Length ? 1 : -1;
    }
}

And then use it:

var myComparer = new MyComparer();
source.OrderBy(s => s, myComparer);

string sorting in C#

4 Answers4