How can I get elements uniquely from an array

Using LINQ can easily solve your problem:

class Program
{
    static string[] ar = new[] { "a", "b", "c", "d", "a", "a", "f", "g",  
        "d", "i", "j", "a","d", "c", "g" };

    static void Main(string[] args)
    {
        var dist = (from a in ar select a).Distinct();// distinct;
        foreach (var v in dist)
            Console.Write(v);
        Console.ReadLine();
    }
}

      

        
        
        
      

    

It produces this output:

abcdfgij