Comments on: What are Hash Tables and how do they work? http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/ Data structures, algorithms, e-books, usefull code and so on... Fri, 05 Sep 2008 21:31:42 +0000 http://wordpress.org/?v=2.0.5 by: David http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-94 Sun, 13 May 2007 20:19:51 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-94 A person who uses scanf without checking the return, in even a trivial example, is either uniformed or a schlock. Further, the example is virtually meatless in regard to hash tables. A person who uses scanf without checking the return, in even a trivial example, is either uniformed or a schlock. Further, the example is virtually meatless in regard to hash tables.

]]> by: Ralph http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-93 Wed, 09 May 2007 05:03:58 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-93 Just stumbled upon your website with wonderful explanations of data-structures, algorithms and more. I just want to say this is great stuff and it really helps people like me which don't come from a traditional programming background. I'm currently trying to understand O-notation to the fullest and I'm finally coming around understanding what the functions represent. One thing you can help out here is with an explanation of O-notation and how you can derive to a specific Order based on given code. Many books/websites will say that a Hashtable is O(1) or a Binary is O(logn) but they don't show you how to arrive to that conclusion. The reason I think this is important is because when we write our own algorithms we'll need a way to find the Order on average-case running time. Doing this for an algorithm I can write is not always easy to know how to do. I know there are methods for calculating algorithm complexity by counting the operations by hand. After, we discard the constants that are lowest and other factors eventually just ending up with the Order itself. This process is what eludes me currently and this is something you can help with I would think. Another good article could be on Bitwise manipulation. I love reading about that stuff as well. Take care!, -Ralph Just stumbled upon your website with wonderful explanations of data-structures, algorithms and more. I just want to say this is great stuff and it really helps people like me which don’t come from a traditional programming background.

I’m currently trying to understand O-notation to the fullest and I’m finally coming around understanding what the functions represent. One thing you can help out here is with an explanation of O-notation and how you can derive to a specific Order based on given code.

Many books/websites will say that a Hashtable is O(1) or a Binary is O(logn) but they don’t show you how to arrive to that conclusion. The reason I think this is important is because when we write our own algorithms we’ll need a way to find the Order on average-case running time. Doing this for an algorithm I can write is not always easy to know how to do.

I know there are methods for calculating algorithm complexity by counting the operations by hand. After, we discard the constants that are lowest and other factors eventually just ending up with the Order itself. This process is what eludes me currently and this is something you can help with I would think.

Another good article could be on Bitwise manipulation. I love reading about that stuff as well.

Take care!,

-Ralph

]]> by: chris http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-92 Tue, 08 May 2007 20:48:21 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-92 Great site. I found it by a lucky "Stumble". Good clear answers. Thank you. Great site. I found it by a lucky “Stumble”. Good clear answers. Thank you.

]]> by: Ross http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-90 Tue, 01 May 2007 22:28:39 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-90 The article was nice, but it didn't actually explain how to add an item to the table. Also, as James said, you do need to go more in depth in how to actually use a hash table. Actually, this article sounded more like it was an explanation of a lookup table, not a hash table. The article was nice, but it didn’t actually explain how to add an item to the table. Also, as James said, you do need to go more in depth in how to actually use a hash table.

Actually, this article sounded more like it was an explanation of a lookup table, not a hash table.

]]> by: James http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-87 Thu, 26 Apr 2007 02:03:46 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-87 Good explanation. However, I think that it either needs expanding or another article to supplement it. I think there should be some mention of the hash function itself and how to create a good hash function if the key is not a simple integer. I also think there needs to be mention of expanding the array when it becomes full. Good explanation. However, I think that it either needs expanding or another article to supplement it. I think there should be some mention of the hash function itself and how to create a good hash function if the key is not a simple integer. I also think there needs to be mention of expanding the array when it becomes full.

]]> by: Somnath Chatterjee http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-86 Wed, 25 Apr 2007 15:20:54 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-86 This contents are really excellent. It is proving fruitful to all sort of ace programmers of corporates. This contents are really excellent. It is proving fruitful to all sort of ace programmers of corporates.

]]> by: Kaell http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-81 Mon, 16 Apr 2007 01:16:41 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-81 Same issue on formatting with firefox and IE on winXP. But great info content. Same issue on formatting with firefox and IE on winXP. But great info content.

]]> by: Danno http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-80 Sun, 15 Apr 2007 20:26:36 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-80 Hallo, This is a rather nice blog, I do believe I'll subscribe. But could you consider fixing the formatting in the code samples? In Firefox on OS X the indentation is lost and makes the programs rather hard to read. Hallo, This is a rather nice blog, I do believe I’ll subscribe. But could you consider fixing the formatting in the code samples? In Firefox on OS X the indentation is lost and makes the programs rather hard to read.

]]> by: buggsy http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-79 Sun, 15 Apr 2007 00:35:00 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-79 Hey David, You misspelled the possessive its. And you're critiquing? Hey David,

You misspelled the possessive its. And you’re critiquing?

]]> by: Chris http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-73 Fri, 13 Apr 2007 23:36:45 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-73 Go easy, David-programming-god. He is teaching about hash tables, not about robust programming. Don't try to search off-topic errors just to sound intelligent, and appreciate the good explanation as we others do. Nice site indeed! Chris Go easy, David-programming-god. He is teaching about hash tables, not about robust programming. Don’t try to search off-topic errors just to sound intelligent, and appreciate the good explanation as we others do.
Nice site indeed!
Chris

]]> by: David http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-69 Fri, 13 Apr 2007 13:56:52 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-69 You use scanf for an integer and don't check it's return? What if I enter 'z'?? And you're teaching? You use scanf for an integer and don’t check it’s return? What if I enter ‘z’?? And you’re teaching?

]]> by: santosh http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-64 Fri, 30 Mar 2007 10:45:59 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-64 Kewl website. really appreciate the effort in making learning colorful . Keep up the good work and also keep updating the website. All my support and kudos to you! Santu Kewl website. really appreciate the effort in making learning colorful . Keep up the good work and also keep updating the website. All my support and kudos to you!
Santu

]]> by: liberty http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-57 Fri, 16 Mar 2007 07:20:35 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-57 Clear and practical explanation. Thanks. Clear and practical explanation. Thanks.

]]> by: espinchi http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-52 Thu, 08 Mar 2007 11:38:41 +0000 http://www.datastructures.info/what-are-hash-tables-and-how-do-they-work/#comment-52 good explanation :-) good explanation :-)

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