CODEWITHSUNDEEP
c#sortinghashtablejquery-ui-sortable
John Ryann
John Ryann

Reputation: 2393

c# Hashtable sorted by Keys

I have a hashtable with keys in alphabetic and values in numeric. how to sort the hashtable based on keys?

ExchangeA, 200
ExchangeV, 100
ExchangeC, 200

to be like this

ExchangeA, 200
ExchangeC, 200
ExchangeV, 100

Upvotes: 7

Views: 65226

Answers (6)

Badar
Badar

Reputation: 1460

I used a list to store keys of Hashtable and sorted it and then dislayed Hashtable using this sorted list. Here is my code:

        List<string> lst = new List<string>();
        foreach (var key2 in ht.Keys)
        {
            lst.Add(key2.ToString());
        }
        lst.Sort();
        foreach (var item in lst)
        {
            Console.WriteLine(string.Format("{0},{1}", item, ht[item.ToString()]));
        }

Upvotes: 0

Rafael Diego Nicoletti
Rafael Diego Nicoletti

Reputation: 463

The simplest way I found to "sort" hashtable is:

var hash = new Hashtable();
var orderedKeys = hash.Keys.Cast<string>().OrderBy(c => c); // supposing you're using string keys
var allKvp = from x in orderedKeys select new{ key = x, value = hash[x] };

However, Im not ordering the original hashtable, only reading its values in an ordered way.

As in other replies, if you need to store your data is sorted way, the best is to use SortedDictionary

Upvotes: 6

Matt Grande
Matt Grande

Reputation: 12157

Use a list instead of a hash (or convert your hash to a dictionary), and do this:

var dictionary = new Dictionary<string, int>();
var l = dictionary.Keys.ToList();
l.Sort();
foreach (var key in l)
{
    Console.WriteLine(dictionary[key]);
}

Upvotes: 1

BrokenGlass
BrokenGlass

Reputation: 160922

You can use a SortedDictionary for this which will do the sorting by key for you. In your case a SortedDictionary<string, int> would work:

SortedDictionary<string, int> dict = new SortedDictionary<string, int>();
dict.Add("Exchange C", 200);
dict.Add("Exchange A", 200);
dict.Add("Exchange V", 100);

foreach (var kvp in dict)
{
    Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
}

Output:

Key = Exchange A, Value = 200
Key = Exchange C, Value = 200
Key = Exchange V, Value = 100

Upvotes: 17

Diego
Diego

Reputation: 18359

Using Linq is easy (using System.Linq):

var sortedList = (from kv in MyDictionary select kv order by kv.Key).ToList<KeyValuePair<string, int>>();

That returns a list of KeyValuePair<string, int>.

Upvotes: 0

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726639

Because of the nature of hash tables, you cannot sort them on the key in place: they organize their keys in buckets based on their hash code, a value outside of hash table's control. However, you can read key-value pairs in whatever order that you like. Here is how you can do it using LINQ:

IDictionary<string, int> d = ...; // your hash table
var ordered = d.OrderBy(p => p.Key).ToList();
foreach (var p in ordered) {
    Console.WriteLine("Key: {0} Value: {1}", p.Key, p.Value);
}

Upvotes: 2

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