## Introduction

Converting a regular expression to a finite automaton means turning a pattern description into a step-by-step machine that checks if a string fits that pattern. It's like creating a specialized robot that follows the rules of the pattern to see if a string matches.

Regular Expressions are the expressions that describe the language accepted by Finite __Automata__. It is the most efficient way to represent any language.

We can easily convert the Regular expressions (also check out some examples of regular expressions)to Finite automata.

Letâ€™s understand the steps required to convert the Regular expressions to Finite automata.

Also See, __Moore Machine__

## Steps To Convert Regular Expressions To Finite Automata

To convert the RE to FA, the method that is popularly used is known as the **Subset method**. This method is used to get FA from the given regular expression.

The steps in this method are given below:-

**Step 1:** Make a transition diagram for a given regular expression, using NFA with Îµ moves.

**Step 2:** Then, Convert this NFA with Îµ to NFA without Îµ.

**Step 3:** Finally, Convert the obtained NFA to equivalent DFA.

Some standard rules help in the conversion of RE to NFA are:-

1.) If RE is in the form **a+b,** it can be represented as:

2.) If RE is in the form **ab, **it can be represented as:

3.) If RE is in the form of **a*, **it can be represented as:

In the next section, we will implement the above method to convert the RE to FA.

Also read - __arden's theorem__