Convert Python 3.x snippet to C#/LINQ.

Question

I want to sort elements of a HashSet<string> and join them by a ; character.

Python interpreter version:

>>> st = {'jhg', 'uywer', 'nbcm', 'utr'}
>>> strng = ';'.join(sorted(s))
>>> strng
'ASD;anmbh;ashgg;jhghjg'

C# signature of a method I seek:

private string getVersionsSorted(HashSet<string> versions);

I can do this without using Linq, but I really want to learn it better.

Many thanks!

Answer 1

Note that HashSets are unordered.

Simple slower version:

String.Join(";", versions.OrderBy(v => v).ToArray());

Custom faster version:

versions.OrderBy(v => v).Join(";");

///<summary>Appends a list of strings to a StringBuilder, separated by a separator string.</summary>
///<param name="builder">The StringBuilder to append to.</param>
///<param name="strings">The strings to append.</param>
///<param name="separator">A string to append between the strings.</param>
public static StringBuilder AppendJoin(this StringBuilder builder, IEnumerable<string> strings, string separator) {
    if (builder == null) throw new ArgumentNullException("builder");
    if (strings == null) throw new ArgumentNullException("strings");
    if (separator == null) throw new ArgumentNullException("separator");

    bool first = true;

    foreach (var str in strings) {
        if (first)
            first = false;
        else
            builder.Append(separator);

        builder.Append(str);
    }

    return builder;
}
///<summary>Combines a collection of strings into a single string.</summary>
public static string Join(this IEnumerable<string> strings, string separator) { return new StringBuilder().AppendJoin(strings, separator).ToString(); }

Cute Faster Version

versions.OrderBy(v => v).Aggregate(new StringBuilder(), 
    (v, sb) => sb.Append(sb.Length > 0 ? ";" : "").Append(v)
).ToString();

.Net 4.0 fastest version:

String.Join(";", versions.OrderBy(v => v));

Answer 2

If you have the option of using .NET 4.0, you could be using the SortedSet<T> class to begin with, which would simplify things greatly, as you just need to call string.Join on your set then.

Otherwise, if you are restricted to .NET 3.5 as it seems, try the following:

private string GetVersionsSorted(ISet<string> versions)
{
    return string.Join(",", versions.OrderBy(s => s).ToArray());
}

(Note: if you were using .NET 4.0 you can also leave out the call to ToArray, which is handy.)

Answer 3

HashSet<string> hash = new HashSet<string>(new string[] { "b", "a", "d" });
string output = hash.OrderBy(str => str).Aggregate((a, b) => a + ";" + b);

output: a;b;d

Answer 4

var versions = new HashSet<string>(new[] { "jhg", "uywer", "nbcm", "utr" });
var result = string.Join(";", versions.OrderBy(x => x).ToArray());
Console.WriteLine(result);