Change the foreach loop into the LINQ query

Question

I stuck in an easy scenario. I have a List<string> object, all of its items has the body of:

item_1_2_generatedGUID //generatedGUID is Guid.NewGuid()

but there may be much more numbers item_1_2_3_4_5_generatedGUID etc

now, I'm wondering how to change that loop into the LINQ's query. Any ideas ?

  string one = "1"; //an exaplme
  string two = "2"; //an exaplme

  foreach (var item in myStringsList)
  {
      string[] splitted = item.Split(new char[] { '_' },
                                     StringSplitOptions.RemoveEmptyEntries);

      if(splitted.Length >= 3)
      {
          if(splitted[1] == one && splitted[2] == two)
          {
              resultList.Add(item);
          }
      }
  }

Answer 1

var result = from s in lst 
             let spl = s.Split('_')
             where spl.Length >= 3 && spl[1] = one  && spl[2] == two
             select s;

Answer 2

Try this:

var query = from item in myStringsList
            let splitted = item.Split(new[] { '_' }, SSO.RemoveEmptyEntries)
            where splitted.Length >= 3
            where splitted[1] == one && splitted[2] == two
            select item;

var resultList = query.ToList();

Answer 3

This is a different approach:

var items = myStringsList.
            Where(x => x.Substring(x.IndexOf("_")).StartsWith(one+"_"+two+"_"));

You probably will need to add a +1 in the IndexOf, but I'm not sure.

What it does is:

• Removes the first item (that's the substring for). In your example, it should be "1_2_3_4_5_generatedGUID"
• Checks the string starts with what you are expecting. In your example: 1_2_

Answer 4

编辑：在第一个“位置”添加了任何内容的模式

var result = items.Where(i => Regex.IsMatch(i, "^[^_]_1_2_"));