https://github.com/lemire/rollinghashcpp

Rolling Hash C++ Library
https://github.com/lemire/rollinghashcpp

hashing universality

Last synced: about 1 year ago
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Rolling Hash C++ Library

• Host: GitHub
• URL: https://github.com/lemire/rollinghashcpp
• Owner: lemire
• Created: 2011-03-11T14:19:01.000Z (about 15 years ago)
• Default Branch: master
• Last Pushed: 2024-03-14T13:37:20.000Z (about 2 years ago)
• Last Synced: 2025-04-09T20:15:23.467Z (about 1 year ago)
• Topics: hashing, universality
• Language: C++
• Homepage:
• Size: 92.8 KB
• Stars: 187
• Watchers: 17
• Forks: 33
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

          
# Randomized rolling hash functions in C++

[![Ubuntu 22.04 CI (GCC 11)](https://github.com/lemire/rollinghashcpp/actions/workflows/ubuntu22.yml/badge.svg)](https://github.com/lemire/rollinghashcpp/actions/workflows/ubuntu22.yml)

License: Apache 2.0

## What is this?

This is a set of C++ classes implementing various recursive n-gram hashing techniques, also called rolling hashing (http://en.wikipedia.org/wiki/Rolling_hash), including:

*   Randomized Karp-Rabin (sometimes called Rabin-Karp)

*   Hashing by Cyclic Polynomials (also known as Buzhash)

*   Hashing by Irreducible Polynomials

This library is used by [khmer](https://github.com/dib-lab/khmer/): the in-memory nucleotide sequence k-mer engine.

 

These are randomized hash functions, meaning that each time you create a new hasher instance, you will

get new hash values for a given input.

##  Code sample

```cpp

        const uint n(3);//hash all sequences of 3 characters

        const uint L(7); // you need 7 bits

        CyclicHash hf(n,L );// if you want 64-bit values replace uint32 by uint64

        for(uint32 k = 0; k