Question

private void button1_Click(object sender, EventArgs e)
{
   string[] array1 = { "C:/folder/a.txt", "C:/folder/b.txt", "C:/folder/c.txt", "C:/folder/d.txt" };

   string[] array2 = { "D:/a.txt", "D:/b.txt", "D:/c.txt", "D:/d.txt" };

   var hash1 = new HashSet<string>(array1);

   var hash2 = new HashSet<string>(array2);

}

I want to compare hash1 and hash2. If a.txt file exists on the hash2 then remove C:/folder/a.txt from hash1. Can we do this without Iterate values ?

Answer 1

If I’m not wrong, then it should be this:

var result = array1.Where(a1 =>  //take only those items from array1, which
              !array2.Any(     //have no such item in array2 
                a2 => a2.Contains(  //that contains
                   a1.Substring(a1.LastIndexOf("/"))))); //a similar filename

var hash1 = new HashSet<string>(result);
var hash2 = new HashSet<string>(array2);

That is, it would be enough to create HashSet with the necessary values already. So all the calculations are done over arrays.