Question

I’m doing an XML reading process in my project. Where I have to read the contents of an XML file. I have achieved it.

Just out of curiosity, I also tried using the same by keeping the XML content inside a string and then read only the values inside the elemet tag. Even this I have achieved. The below is my code.

string xml = <Login-Form>
                 <User-Authentication>
                     <username>Vikneshwar</username>
                     <password>xxx</password>
                 </User-Authentication>

                 <User-Info>
                     <firstname>Vikneshwar</firstname>
                     <lastname>S</lastname>
                     <email>[e-mail]</email>
                 </User-Info>
             </Login-Form>";
        XDocument document = XDocument.Parse(xml);

var block = from file in document.Descendants("client-authentication")
            select new
            {
                Username = file.Element("username").Value,
                Password = file.Element("password").Value,
            };

foreach (var file in block)
{
    Console.WriteLine(file.Username);
    Console.WriteLine(file.Password);
}

Similarly, I obtained my other set of elements (firstname, lastname, and email). Now my curiosity draws me again. Now I’m thinking of doing the same using the string functions?

The same string used in the above code is to be taken. I’m trying not to use any XMl related classes, that is, XDocument, XmlReader, etc. The same output should be achieved using only string functions. I’m not able to do that. Is it possible?

Answer 1

It can be done without regular expressions, like this:

string[] elementNames = new string[]{ "<username>", "<password>"};
foreach (string elementName in elementNames)
{
    int startingIndex = xml.IndexOf(elementName);
    string value = xml.Substring(startingIndex + elementName.Length,
        xml.IndexOf(elementName.Insert(1, "/")) 
        - (startingIndex + elementName.Length));
    Console.WriteLine(value);
}

With a regular expression:

string[] elementNames2 = new string[]{ "<username>", "<password>"};
foreach (string elementName in elementNames2)
{
    string value = Regex.Match(xml, String.Concat(elementName, "(.*)",
        elementName.Insert(1, "/"))).Groups[1].Value;
    Console.WriteLine(value);
}

Of course, the only recommended thing is to use the XML parsing classes.