从特定索引字符中删除字符

Question

I would like to know how can i remove characters in a string from a specific index like :

string str = "this/is/an/example"

I want to remove all characters from the third '/' including so it would be like this:

str = "this/is/an"

I tried with substring and regex but i cant find a solution.

Answer 1

Using string operations:

str = str.Substring(0, str.IndexOf('/', str.IndexOf('/', str.IndexOf('/') + 1) + 1));

Using regex:

str = Regex.Replace(str, @"^(([^/]*/){2}[^/]*)/.*$", "$1");

Answer 2

This regex is the answer: ^[^/]*\\/[^/]*\\/[^/]* . It will capture the first three chunks.

var regex = new Regex("^[^/]*\\/[^/]*\\/[^/]*", RegexOptions.Compiled);
var value = regex.Match(str).Value;

Answer 3

To get "this/is/an":

string str = "this/is/an/example";
string new_string = str.Remove(str.LastIndexOf('/'));

If you need to keep the slash:

string str = "this/is/an/example";
string new_string = str.Remove(str.LastIndexOf('/')+1);

This expects there to be at least one slash. If none are present, you should check it beforehand to not throw an exception:

string str = "this.s.an.example";
string newStr = str;
if (str.Contains('/'))
    newStr = str.Remove(str.LastIndexOf('/'));

If its importaint to get the third one, make a dynamic method for it, like this. Input the string, and which "folder" you want returned. 3 in your example will return "this/is/an":

    static string ReturnNdir(string sDir, int n)
    {
        while (sDir.Count(s => s == '/') > n - 1)
            sDir = sDir.Remove(sDir.LastIndexOf('/'));
        return sDir;
    }

Answer 4

I think the best way of doing that it's creating a extension

     string str = "this/is/an/example";
     str = str.RemoveLastWord();

     //specifying a character
     string str2 = "this.is.an.example";
     str2 = str2.RemoveLastWord(".");

With this static class:

  public static class StringExtension
 {
   public static string RemoveLastWord(this string value, string separator = "")
   {
     if (string.IsNullOrWhiteSpace(value))
        return string.Empty;
     if (string.IsNullOrWhiteSpace(separator))
        separator = "/";

     var words = value.Split(Char.Parse(separator));

     if (words.Length == 1)
        return value;

     value = string.Join(separator, words.Take(words.Length - 1));

     return value;
  }
}