title: Looking for a clear definition of what a "tokenizer", "parser" and "lexers" are and how they are related to each other and used?
body: <p>I am looking for a clear definition of what a "tokenizer", "parser" and "lexer" are and how they are related to each other (e.g., does a parser use a tokenizer or vice versa)? I need to create a program will go through c/h source files to extract data declaration and definitions. </p>
  
  <p>I have been looking for examples and can find some info, but I really struggling to grasp the underlying concepts like grammar rules, parse trees and abstract syntax tree and how they interrelate to each other. Eventually these concepts need to be stored in an actual program, but 1) what do they look like, 2) are there common implementations.</p>
  
  <p>I have been looking at Wikipedia on these topics and programs like Lex and Yacc, but having never gone through a compiler class (EE major) I am finding it difficult to fully understand what is going on.</p>