Find a string between 2 known values

I need to be able to extract a string between 2 tags for example: "00002" from "morenonxmldata<tag1>0002</tag1>morenonxmldata"

I am using C# and .NET 3.5.

Solution 1:

  Regex regex = new Regex("<tag1>(.*)</tag1>");
  var v = regex.Match("morenonxmldata<tag1>0002</tag1>morenonxmldata");
  string s = v.Groups[1].ToString();

Or (as mentioned in the comments) to match the minimal subset:

  Regex regex = new Regex("<tag1>(.*?)</tag1>");

Regex class is in System.Text.RegularExpressions namespace.

Solution 2:

Solution without need of regular expression:

string ExtractString(string s, string tag) {
     // You should check for errors in real-world code, omitted for brevity
     var startTag = "<" + tag + ">";
     int startIndex = s.IndexOf(startTag) + startTag.Length;
     int endIndex = s.IndexOf("</" + tag + ">", startIndex);
     return s.Substring(startIndex, endIndex - startIndex);
}

Solution 3:

A Regex approach using lazy match and back-reference:

foreach (Match match in Regex.Matches(
        "morenonxmldata<tag1>0002</tag1>morenonxmldata<tag2>abc</tag2>asd",
        @"<([^>]+)>(.*?)</\1>"))
{
    Console.WriteLine("{0}={1}",
        match.Groups[1].Value,
        match.Groups[2].Value);
}

Solution 4:

Extracting contents between two known values can be useful for later as well. So why not create an extension method for it. Here is what i do, Short and simple...

  public static string GetBetween(this string content, string startString, string endString)
    {
        int Start=0, End=0;
        if (content.Contains(startString) && content.Contains(endString))
        {
            Start = content.IndexOf(startString, 0) + startString.Length;
            End = content.IndexOf(endString, Start);
            return content.Substring(Start, End - Start);
        }
        else
            return string.Empty;
    }