Thread: Own lil' "database" ?

  1. #1
    Registered User
    Join Date
    Mar 2008

    Own lil' "database" ?


    I'm looking for some kind of tutorial for writing a tool that does the following:
    It reads multiple values and compares them to a small database and then reads a string from the database which is assigned to the values.
    So lets say we gather val1, val2 and val3 with the program it would be cool to have a database file with a format like that:
    /* val1, val2, val3, matching string */
    0, 0, 0, "Stringallzero"
    0, 1, 0, "Stringval2is1"
    473, 2, 5, "Yet another string"

    The "," as separator would work for me as I won't have to use them in the strings.
    Can this be done somehow easily and can the performance keep up with a "in-code" database using switch() - which is my current solution:
    switch (val 1)
       case 0: switch (val 2)
    This is ugly and makes the binaries quite big...and the database can't be altered without re-compiling which is quite annoying, too...

    So if anyone has a piece of code or knows some good tutorial please let me know


  2. #2
    Technical Lead QuantumPete's Avatar
    Join Date
    Aug 2007
    London, UK
    can the performance keep up with a "in-code" database using switch
    Nope, opening a file and reading from it, will in most cases (certainly the first time) have to hit the hard drive, which is a slow operation. However, on modern computers you might well not notice a difference if the file isn't several Mb big.

    I assume that when you say database, you actually mean datafile. Have a look at the FAQ for information on how to read from files!

    "No-one else has reported this problem, you're either crazy or a liar" - Dogbert Technical Support
    "Have you tried turning it off and on again?" - The IT Crowd

  3. #3
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Instead of coming up with your own data format and then writing a parser for it, you should consider using SQLite, which is a relational database engine that can easily be embedded into your program.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  4. #4
    Crazy Fool Perspective's Avatar
    Join Date
    Jan 2003
    I'd recommed berkely DB since you basically just want to map keys to string values. It can be run from disk or embedded as well.

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