Question

What I have going on is two files, one file contains:

Orange
Apple

The second file contains
Orange~1.txt
Orange~2321.txt
Apple~12.txt
Apple~23.txt
Ap~23.txt
OROR~23.txt

What I need to do is is if the first file matches a line in the second file, copy that file out to a new directory. What I have going on now never finds any matching items.

string[] content = File.ReadAllLines(@"C:\Cact.txt");
            string[] mastercontent = File.ReadAllLines(masterdin + "\\Master.txt");
            foreach (string con in content)
            {
                if (mastercontent.Contains(con))
                {
                    File.Copy(masterfolder + "\\" + con, masterdin);
                }
            }

Answer 1

You’re calling the LINQ Contains method on the array, which will return true if the array contains a string which is exactly equal to con.

The simplest solution is to change mastercontent to a single string by calling File.ReadAllText.
This will call String.Contains, and will check whether con appears anywhere in the large string. (This would behave differently if con has newlines, but it can’t)

Alternatively, you can use LINQ to check whether mastercontent has any strings containing con, like this:

if (mastercontent.Any(m => m.Contains(con))

EDIT: To match case-insensitively, you can change it to the following:

if (mastercontent.Any(m => 0 >= m.IndexOf(con, StringComparison.OrdinalIgnoreCase))