Otherwise, if you need to write it from scratch, you need to first figure out if you need a tokenizer or "lexical analyser".
Since all regular languages accept finite acceptors, a regular expression must also be able to accept a finite automaton.
But let us first look at the method for converting a regular expression to an NFA. Probably the most famous algorithm for doing this conversion is Thompson's algorithm. This algorithm is not the most efficient, but it ensures that any regular expression (assuming that its syntax is correct) will be successfully converted to an NFA. Regular Expressions and Converting to a NFA. Contents. Definition Creating a Regular Expression Converting to a NFA. Definition. A regular expression is another representation of a regular language, and is defined over an alphabet (defined as Σ). NFA FROM RE AIM: To write a C program to convert the regular expression to NFA. ALGORITHM: 1. Start the program. 2. Declare all necessary header files. 3. Define the main function. 4. Declare the variables and initialize variables r & c to ‘0’. 5. Use a for loop within another for loop to /5(8).
For knowledge of many of the general tools, menus, and windows used to create an automaton, one should first read the tutorial on finite automata.
One should eventually see a blank screen that looks like the screen below. Now one can enter whatever expression that one wishes.
One such expression is in the screen below. One can either type it in directly, or load the file regExprToNfa.
Converting to a NFA After typing in an expression, there is nothing else that can be done in this editor window besides converting it to an NFA, so let's proceed to that. If one uses the example provided earlier, this screen should come up after resizing the window a little.
You should now see, perhaps with a little resizing, a screen like this You're probably wondering what exactly you just did.
Basically, you broke the regular expression into three sub-expressions, which were united into one expression by the implicit concatenation operator. Whenever you click on an expression or sub-expression through this button, it will subdivide according to the last unique operation in the order of operations.
Thus, since concatenations are the last operation to be performed on the given expression, the expression is divided according to that operator.
Now, let's make our first transition. These types of transitions are all that are needed to create a nondeterministic automaton. Now, try to create a transition from q0 to q4. However, you should be warned that although the transition may be correct, you must create the transitions in the correct order.
When done, your screen should resemble the one below.
Continue decomposing the expression using the tools provided. In any event, when done, you should see a screen resembling the one below.
When finished, click the "Export" button, and you now have a nondeterministic finite automaton that you may use as you see fit. This concludes our brief tutorial on regular expressions and using them to build NFAs.Regular Expression to NFA (Non-Deterministic Finite Automata) Visualize the Thompson-McNaughton-Yamada construction NFA for a given regular expression.
So a change in A will generate a change in Y according to the this formula: (12) ΔY = kΔA. where k = 1/(1 – c*(1-t) + m) and is the expression for the expenditure multiplier.
RESULT: Thus the C program to convert regular expression to NFA has been executed and the output has been verified successfully. SIMULATION OF DFA AIM: To write a C program to convert the regular expression to DFA/5(8). I am trying to write a program that will accept a string that describes a regular expression.
For instance: 10(0U1)* Where the U is the union operator and the * . Regular Expressions and Converting to a NFA. Contents. Definition Creating a Regular Expression Converting to a NFA.
Definition. A regular expression is another representation of a regular language, and is defined over an alphabet (defined as Σ). Yes.
All NFA can be converted to DFA. In fact, all NFA can be converted into minimal DFA via a closure algorithm. The typical use is to construct a regular expression NFA via Thompson’s construction, with epsilon (NULL) transitions.
Then NFA to DF.