List sorting which contains string starting with underscore

Question

So here is what I got: I have a list with these strings in it: "student", "Students", "students", "Student" and "_Students".

What I have done:

List<string> sort = new List<string>() { "student", "Students", "students", "Student","_Students" };
List<string> custsort = sort.OrderBy(st => st[0]).ThenBy(s => s.Length)
                                                             .ToList();

But this gives me this sort:

Student
Students
_Students
student
students

And what I want is:

_Students
Student
Students
student
students

I can't figure it out how to sort them because that damn underscore is located between the upperCase and lowerCase letters in the ASCII table.

Answer 1

You can use a regex to determine whether the first character is a letter and apply a weight to it.

int GetWeight(char c)
{
    return Regex.IsMatch(c.ToString(), @"[a-zA-Z]") ? c : 0;
}

List<string> sort = new List<string>() { "student", "Students", "students", "Student","_Students" };
List<string> custsort =
    sort.OrderBy(st => GetWeight(st[0]))
        .ThenBy(s => s.Length)
        .ToList();

This way if you need any other special rules you can modify the GetWeight function and your Linq will be unaffected.