https://github.com/jamesroutley/write-a-hash-table

✏️ Learn how to write a hash table in C
https://github.com/jamesroutley/write-a-hash-table

c data-structures hash-tables tutorial

Last synced: 6 days ago
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✏️ Learn how to write a hash table in C

• Host: GitHub
• URL: https://github.com/jamesroutley/write-a-hash-table
• Owner: jamesroutley
• License: mit
• Created: 2017-08-04T13:05:13.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2023-12-16T14:30:33.000Z (12 months ago)
• Last Synced: 2024-11-29T04:02:32.551Z (13 days ago)
• Topics: c, data-structures, hash-tables, tutorial
• Homepage:
• Size: 51.8 KB
• Stars: 3,496
• Watchers: 66
• Forks: 280
• Open Issues: 19
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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README

        
[](/README.md) [](/.translations/fr/README.md)

# Write a hash table in C

[Hash tables](https://en.wikipedia.org/wiki/Hash_table) are one of the most useful data structures. Their quick and scalable

insert, search and delete make them relevant to a large number of computer

science problems.

In this tutorial, we implement an [open-addressed](https://en.wikipedia.org/wiki/Open_addressing), [double-hashed](https://en.wikipedia.org/wiki/Double_hashing) hash table in

C. By working through this tutorial, you will gain:

- Understanding of how a fundamental data structure works under the hood

- Deeper knowledge of when to use hash tables, when not to use them, and how

  they can fail

- Exposure to new C code

C is a great language to write a hash table in because:

- The language doesn't come with one included

- It is a low-level language, so you get deeper exposure to how things work at a

  machine level

This tutorial assumes some familiarity with programming and C syntax. The code

itself is relatively straightforward, and most issues should be solvable with a

web search. If you run into further problems, please open a GitHub

[Issue](https://github.com/jamesroutley/write-a-hash-table/issues).

The full implementation is around 200 lines of code, and should take around an

hour or two to work through.

## Contents

1. [Introduction](/01-introduction)

2. [Hash table structure](/02-hash-table)

3. [Hash functions](/03-hashing)

4. [Handling collisions](/04-collisions)

5. [Hash table methods](/05-methods)

6. [Resizing tables](/06-resizing)

6. [Appendix: alternative collision handling](/07-appendix)

## Credits

This tutorial was written by [James Routley](https://twitter.com/james_routley),

who blogs at [routley.io](https://routley.io).