Question

This is the code:

if (@"d:\Keywords.txt".Contains(line))
{
}
else
{
    w.WriteLine(line);
}

I see in notepad that in Keywords.txt there is the line:

Daniel

And line is now Daniel
But it still doing the w.WriteLine(line);

Why is that ?

Answer 1

"d:\Keywords.txt" is a string, so you are checking if line is contained within "d:\Keywords.txt" string (it is not, that why it goes to else). If you want to load contents of files then you can use (e.g.) File.ReadAllLines:

var lines = File.ReadAllLines("d:\Keywords.txt"); 
if(lines.Contains(line))  
{
    // do something 
}

Full list of File class methods are available @MSDN File Class