How to swap Hashtable's key with Value.

Question

How to swap Hashtable's key with Value.
I have solved it by following.

Is there any other solution?

class Program
    {
        static void Main(string[] args)
        {
            Hashtable hsTbl = new Hashtable();

            hsTbl.Add(1, "Suhas");
            hsTbl.Add(2, "Madhuri");
            hsTbl.Add(3, "Om");
            List<object> keyList = new List<object>();
            List<object> ValList = new List<object>();

            Console.WriteLine("Key          Value");
            foreach (DictionaryEntry item in hsTbl)
            {
                Console.WriteLine(item.Key + "      " + item.Value);
                keyList.Add(item.Value);
                ValList.Add(item.Key);

             }
            hsTbl.Clear()

//Swapping

for (int i = 0; i < keyList.Count; i++)
            {
                hsTbl.Add(keyList[i], ValList[i]);
            }

//will display hashtable after swapping

            foreach (DictionaryEntry item in hsTbl)
            {
                Console.WriteLine(item.Key + "      " + item.Value);

}
}
}

Vulpes · Answer

You could do it slightly simpler using an additional array and the CopyTo method rather than 2 lists but without creating an additional HashTable as follows: using System; using System.Collections; class Program { static void Main() { Hashtable hsTbl = new Hashtable(); hsTbl.Add(1 Suhas); hsTbl.Add(2 Madhuri); hsTbl.Add(3 Om); DictionaryEntry[] entries = new DictionaryEntry[hsTbl.Count]; hsTbl.CopyTo(entries 0); hsTbl.Clear(); foreach(DictionaryEntry de in entries) hsTbl.Add(de.Value de.Key); // check it worked foreach(DictionaryEntry de in hsTbl) { Console.WriteLine({0} : {1} de.Key de.Value); } } } Note that in general no method is guaranteed to work because some of the values in the original hashtable may be duplicated and therefore be unsuitable as keys.

Santhosh Kumar Jayaraman · Answer

You can try this one also. Creating another hashtable and adding values to it from existing one Hashtable hsTbl = new Hashtable(); hsTbl.Add(1 Suhas); hsTbl.Add(2 Madhuri); hsTbl.Add(3 Om); IDictionaryEnumerator myEnumerator = hsTbl.GetEnumerator(); Hashtable hstbl2 = new Hashtable(); while (myEnumerator.MoveNext()) { hstbl2.Add(myEnumerator.Value myEnumerator.Key); }

Suhas D · Answer

@ Vulpes :Yes This is more closer to answer and acceptable. @ Santhosh Kumar : Your approch is also right but I did want to create new Hashtable for this.