what's the point?

This is a discussion on what's the point? within the C Programming forums, part of the General Programming Boards category; I've been reading a book about data structures and today I read through the chapter on hash tables. I understand ...

  1. #1
    Registered User Draco's Avatar
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    what's the point?

    I've been reading a book about data structures and today I read through the chapter on hash tables. I understand the topic well, but the one thing the book didn't really cover is the point to using hash tables. I can't think of any real use where a hash table will be more effective than something else(I do know that hash tables are used later in the book, for things like compression and advanced filing/searching). Maybe I'm missing some of the point of hash tables.

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    Obsessed with C chrismiceli's Avatar
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    i think ext2 uses hash tables to access files quicker, if I remember right.
    // for those who don't know, ext2 is a filesystem like fat32 or ntfs
    Last edited by chrismiceli; 08-18-2003 at 06:44 AM.

  3. #3
    ATH0 quzah's Avatar
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    That's exactly right. The point of a hash table is faster searching. Consider a linked list with many entries. To find a given entry, you start at the beginning, and increment through the list until you find the one you want.

    With a hash table, you have automaticly (based on the hash key) reduced your search times by N amount, where N is the number of buckets in your hash table.

    So if you have 100 entries, and 10 buckets, you have effectively reduced your search time to 1/10th of what it would normally take.

    Quzah.
    Hope is the first step on the road to disappointment.

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