What is parsing in terms that a new programmer would understand?

parsing new-operator
Daisetsu picture Daisetsu · May 29, 2010 · Viewed 112k times · Source

I am a college student getting my Computer Science degree. A lot of my fellow students really haven't done a lot of programming. They've done their class assignments, but let's be honest here those questions don't really teach you how to program.

I have had several other students ask me questions about how to parse things, and I'm never quite sure how to explain it to them. Is it best to start just going line by line looking for substrings, or just give them the more complicated lecture about using proper lexical analysis, etc. to create tokens, use BNF, and all of that other stuff? They never quite understand it when I try to explain it.

What's the best approach to explain this without confusing them or discouraging them from actually trying.

Answer

LukeN picture LukeN · May 29, 2010

I'd explain parsing as the process of turning some kind of data into another kind of data.

In practice, for me this is almost always turning a string, or binary data, into a data structure inside my Program.

For example, turning

":Nick!User@Host PRIVMSG #channel :Hello!"

into (C)

struct irc_line {
    char *nick;
    char *user;
    char *host;
    char *command;
    char **arguments;
    char *message;
} sample = { "Nick", "User", "Host", "PRIVMSG", { "#channel" }, "Hello!" }

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