Remove Duplicate Lines From Text File?

Question

Given an input file of text lines, I want duplicate lines to be identified and removed. Please show a simple snippet of C# that accomplishes this.

Answer 1

I am new to .net & have written something more simpler,may not be very efficient.Please fill free to share your thoughts.

class Program
{
    static void Main(string[] args)
    {
        string[] emp_names = File.ReadAllLines("D:\\Employee Names.txt");
        List newemp1 = new List();

        for (int i = 0; i < emp_names.Length; i++)
        {
            newemp1.Add(emp_names[i]);  //passing data to newemp1 from emp_names
        }

        for (int i = 0; i < emp_names.Length; i++)
        {
            List temp = new List();
            int duplicate_count = 0;

            for (int j = newemp1.Count - 1; j >= 0; j--)
            {
                if (emp_names[i] != newemp1[j])  //checking for duplicate records
                    temp.Add(newemp1[j]);
                else
                {
                    duplicate_count++;
                    if (duplicate_count == 1)
                        temp.Add(emp_names[i]);
                }
            }
            newemp1 = temp;
        }
        string[] newemp = newemp1.ToArray();  //assigning into a string array
        Array.Sort(newemp);
        File.WriteAllLines("D:\\Employee Names.txt", newemp); //now writing the data to a text file
        Console.ReadLine();
    }
}