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Automata-based programming is a programming paradigm in which the program or its part is thought of as a model of a finite state machine (FSM) or any other (often more complicated) formal automaton (see automata theory). Sometimes a potentially-infinite set of possible states is introduced, and such a set can have a complicated structure, not just an enumeration. FSM-based programming is generally the same, but, formally speaking, doesn't cover all possible variants as FSM stands for finite state machine and automata-based programming doesn't necessarily employ FSMs in the strict sense. The following properties are key indicators for automata-based programming: # The time period of the program's execution is clearly separated down to the ''steps of the automaton''. Each of the ''steps'' is effectively an execution of a code section (same for all the steps), which has a single entry point. Such a section can be a function or other routine, or just a cycle body. The step section might be divided down to subsection to be executed depending on different states, although this is not necessary. # Any communication between the steps is only possible via the explicitly noted set of variables named ''the state''. Between any two steps, the program (or its part created using the automata-based technique) can not have implicit components of its state, such as local (stack) variables' values, return addresses, the current instruction pointer etc. That is, the state of the whole program, taken at any two moments of entering the step of the automaton, can only differ in the values of the variables being considered as the state of the automaton. The whole execution of the automata-based code is a (possibly explicit) cycle of the automaton's steps. Another reason to use the notion of automata-based programming is that the programmer's style of thinking about the program in this technique is very similar to the style of thinking used to solve math-related tasks using Turing machine, Markov algorithm etc. == Example == Consider a program in C that reads a text from ''standard input stream'', line by line, and prints the first word of each line. It is clear we need first to read and skip the leading spaces, if any, then read characters of the first word and print them until the word ends, and then read and skip all the remaining characters until the end-of-line character is encountered. Upon reaching the end of line character (regardless of the stage), we restart the algorithm from the beginning, and upon encountering the ''end of file'' condition (regardless of the stage), we terminate the program. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Automata-based programming」の詳細全文を読む スポンサード リンク
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