Thread: Finite state machine

hello i'm wildan from indonesia,
i just begin to studying C language then i have a home work. i can't solved it..

A finite state machine (FSM) consists of a set of states, a set of transitions,
and a string of input data. In the FSM of Fig. 6.19 , the named ovals represent
states, and the arrows connecting the states represent transitions. The
FSM is designed to recognize a list of C identifiers and nonnegative integers,
assuming that the items are ended by one or more blanks and that a period
marks the end of all the data. The following table traces how the diagrammed
machine would process a string composed of one blank, the digits 9 and 5, two
blanks, the letter K, the digit 9, one blank, and a period. The machine begins



in the start state.
Trace of Fig. 6.19 FSM on data “ 95 K9 .”
State Next Character Transition
start ' ' 3
start '9' 1
build_num '5' 9
build_num ' ' 10
number Output number message
start ' ' 3
start 'K' 4
build_id '9' 6
build_id ' ' 8
identifier Output identifier message
start ' . ' 2
stop
Write a program that uses an enumerated type to represent the names
of the states. Your program should process a correctly formatted line of data,
identifying each data item. Here is a sample of correct input and output.
Input :
rate R2D2 48 2 time 555666
Output :
rate – Identifier
R2D2 – Identifier
48 – Number
2 – Number
time – Identifier
555666 – Number
Use the following code fragment in main , and design function transition
to return the next state for all the numbered transitions of the finite state
machine. If you include the header file ctype.h , you can use the library
function isdigit which returns 1 if called with a digit character, 0 otherwise.
Similarly, the function isalpha checks whether a character is a letter.
When your program correctly models the behavior of the FSM shown,
extend the FSM and your program to allow optional signs and optional
fractional parts (i.e., a decimal point followed by zero or more digits)
in numbers.

Code:

current_state = start;
do {
if (current_state == identifier) {
printf(" - Identifier\n");
current_state = start;
} else if (current_state == number) {
printf(" - Number\n");
current_state = start;
}
scanf("%c", &transition_char);
if (transition_char != ' ')
printf("%c", transition_char);
current_state = transition(current_state, transition_char);
} while (current_state != stop);