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    <p>You're basically writing a very simple state machine - use functions to represent every state: (I'll use random pseudocode, since you didn't specify a language)</p> <pre><code>get_information(): return get_record() ask_record(): record = read_line() return () if !record return ask_y(record) ask_x(record): x = read_line() return ask_record() if !x return ask_y(record, x) ask_y(record, x): y = read_line() return ask_x(record) if !y return ask_continue(record, x, y) ask_continue(record, x, y) continue = read_line() return ask_y(record, x) if !continue return (record, x, y) </code></pre> <p>this is a trivial approach. In some languages the call stack will grow, in others it won't. If you have a language which causes the stack to grow, you can use trampolines to prevent it, by rewriting <code>get_information</code> to do:</p> <pre><code>x = get_information while x is function: x=x() return x ask_x(record): x = read_line() return (lambda: ask_record()) if !x return (lambda: ask_y(record, x)) </code></pre> <p>Or even abstracting the question and memory address of result in some <code>question</code> structure:</p> <pre><code>struct question { question *next, *prev; char prompt[]; char **result; } </code></pre> <p>and then running in a loop, calling <code>question* run_question(question*)</code>, going to ->next, or ->prev depending on the answer, until the result is NULL (as a stop condition, when results are filled in and no questions are left).</p> <p>The last solution is probably the most "normal one" if you use an imperative language with direct pointer access.</p>
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