Where can I find examples of data parsers in C#?

Question

Python

I want to learn how to write data parsers. For example ini-like files. Well, or let's say XML. Where to begin? As I understand it, you need to split the text into tokens and then build a DOM tree, or what? I looked around for examples but found nothing intelligible. Arrange an example in C# or Python.
PS I'm not interested in ready-made parsers. I'm interested in how to properly parse the text into tokens and what to do with them. How to understand where the first level of complexity is acceptable, and where the second, etc.

Answer 1

by xml and this by xml
by ini and this by ini

Answer 2

https://www.google.com.ua/search?q=c%23+ini+parsing