How can I define variables in LINQ?

Question

This code:

string[] files = {"test.txt",      "test2.txt",      "notes.txt",      "notes.doc",      "data.xml",      "test.xml",      "test.html",      "notes.txt",      "test.as"};  files.ToList().ForEach(f => Console.WriteLine(         f.Substring(             f.IndexOf('.') + 1,              f.Length - f.IndexOf('.') - 1             )     )); 

produces this list:

txt txt txt doc xml xml html txt as 

Is there some way to make f.IndexOf('.') a variable so that in more complex LINQ queries I have this defined in one place?

Answer 1

If you were using Linq then you could use the let keyword to define an inline variable (the code posted in the question isn't actually using Linq).

var ext = from file in files           let idx = f.LastIndexOf('.') + 1           select file.Substring(idx); 

However for the specific scenario you've posted I'd recommend using Path.GetExtension instead of parsing the string yourself (for example, your code will break if any of the files have a . in the file name).

var ext = from file in files select Path.GetExtension(file).TrimStart('.'); foreach (var e in ext) {     Console.WriteLine(e); }