正则表达式检查以查找具有给定字符的项目

Question

I've a class

public class MyClass
        {
            public MyClass(int id, string name)
            {
                this.Id = id;
                //Id = id;
                this.Name = name;
            }
            public int Id { get; set; }
            public string Name { get; set; }
        }

I created a list of MyClass type and added few items to it

    List<MyClass> lst = new List<MyClass>();
    lst.Add(new MyClass(1, "Name1"));
    lst.Add(new MyClass(2, "ab****cdefg"));
    lst.Add(new MyClass(3, "he*llo"));
    lst.Add(new MyClass(4, "pa**yed"));
    lst.Add(new MyClass(5, "Names2"));
    lst.Add(new MyClass(6, "hi******iiii"));
    lst.Add(new MyClass(7, "so*me"));
    lst.Add(new MyClass(8, "so**rt"));
    lst.Add(new MyClass(9, "*"));
    lst.Add(new MyClass(10, "**"));
    lst.Add(new MyClass(11, "t*e*s*t"));
    lst.Add(new MyClass(12, "t**e**s**t"));

How can i find items having only one * in name field in a list and two ** in name field in another list. I'ld like to do it by linq or regex, any other good option is also invited. I tried using contains method but got all items having * .

var singlestar = lst.Where(x => x.Name.Contains("*")).ToList();

Answer 1

this should match names with just one "\\*" and two "\\*\\*"

var singlestar = lst.Where(x =>Regex.Matches(x.Name,  "\\*").Count == 1).ToList();
var twostar = lst.Where(x =>Regex.Matches(x.Name,  "\\*\\*").Count == 1).ToList();

Answer 2

If you only need single stars I suspect those shouldn't contain at least 2 stars. If stars might show up elsewhere a regex might be better.

var singlestar = lst.Where(x => (x.Name.Contains("*") and !(x.Name.Contains("**")))).ToList();

var doublestar = lst.Where(x => (x.Name.Contains("**") and !(x.Name.Contains("***")))).ToList();

Or with Regex

Regex rgx1 = new Regex(@"^[^*]*\\*[^*]*$");
Regex rgx2 = new Regex(@"^[^*]*\\*\\*[^*]*$");
var singlestar = lst.Where(x => rgx1.IsMatch(x.Name)).ToList();

var doublestar = lst.Where(x => rgx2.IsMatch(x.Name)).ToList();

With the Regex, there should be no other stars anywhere else in the name.