Comments on: hash tables are as delicious as a pretty nice steak http://eviljim.com/archives/2007/03/hash-tables-are-as-delicious-as-a-pretty-nice-steak/ jim reardon (from joliet / shorewood, illinois, and former microsoft intern guy) Mon, 12 Sep 2011 02:53:30 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: eviljim http://eviljim.com/archives/2007/03/hash-tables-are-as-delicious-as-a-pretty-nice-steak/comment-page-1/#comment-3995 eviljim Fri, 16 Mar 2007 00:34:24 +0000 http://eviljim.com/archives/2007/03/hash-tables-are-as-delicious-as-a-pretty-nice-steak/#comment-3995 A hash is basically just an array, except it's indexed by anything (instead of just a number). It provides quick lookup time too. So, for example, if you have a list of people and their addresses, you could have a hash where "bob" -> "123 west st" "sam" -> "234 west st" "julie" -> "123 west st" # shacking up with bob. sinner. So the advantage is if you want bob's address, you just say $hash{"bob"}, and there you have it. (Lookup time here is constant, no matter the size of the hash, as opposed to other data structures where you might spend more time finding the entry for "bob"). The thing is, since it's not stored in numerical order (like an array, where you have a first element, second element, etc...) there's no real concept of "what is the 2nd item?" A hash is basically just an array, except it’s indexed by anything (instead of just a number). It provides quick lookup time too.

So, for example, if you have a list of people and their addresses, you could have a hash where

“bob” -> “123 west st”
“sam” -> “234 west st”
“julie” -> “123 west st” # shacking up with bob. sinner.

So the advantage is if you want bob’s address, you just say $hash{“bob”}, and there you have it. (Lookup time here is constant, no matter the size of the hash, as opposed to other data structures where you might spend more time finding the entry for “bob”).

The thing is, since it’s not stored in numerical order (like an array, where you have a first element, second element, etc…) there’s no real concept of “what is the 2nd item?”

]]> By: Brian http://eviljim.com/archives/2007/03/hash-tables-are-as-delicious-as-a-pretty-nice-steak/comment-page-1/#comment-3994 Brian Fri, 16 Mar 2007 00:25:53 +0000 http://eviljim.com/archives/2007/03/hash-tables-are-as-delicious-as-a-pretty-nice-steak/#comment-3994 Alright, I looked up "hash table" on wikipedia just so I could understand what your post is about. All it did was reconfirm my ineptitude for computer programming. I could stare at that explanation for hours and I still won't understand why the existance of a hash table is neccessary. Alright, I looked up “hash table” on wikipedia just so I could understand what your post is about. All it did was reconfirm my ineptitude for computer programming. I could stare at that explanation for hours and I still won’t understand why the existance of a hash table is neccessary.

]]> By: Brian http://eviljim.com/archives/2007/03/hash-tables-are-as-delicious-as-a-pretty-nice-steak/comment-page-1/#comment-3983 Brian Thu, 15 Mar 2007 04:23:22 +0000 http://eviljim.com/archives/2007/03/hash-tables-are-as-delicious-as-a-pretty-nice-steak/#comment-3983 You've really narrowed your audience since moving to Google. You’ve really narrowed your audience since moving to Google.

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