Communications of the ACM
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How the “Frontier” Became the Slogan of Uncontrolled AI
Artificial intelligence (AI) has been billed as the next frontier of humanity: the newly available expanse whose exploration …
From Daniel Lemire's Blog
JavaScript hashing speed comparison: MD5 versus SHA-256
Hashing algorithms convert input data into a fixed-size string of characters, known as a hash value or digest. These algorithms are one-way functions, meaning the...
From Daniel Lemire's Blog
Counting the digits of 64-bit integers
Given an integer in software, you may want to know how many decimal digits it needs. For example, the integer 100 requires 3 digits, the integer 9999 requires 4...
From Daniel Lemire's Blog
How does your URL parser handle Unicode?
Most strings today in software are Unicode strings. It means that you can include mathematical symbols, emojis and so forth. There are many different versions of...
From Daniel Lemire's Blog
Efficient In-Place UTF-16 Unicode Correction with ARM NEON
Modern-day text in software can be expected to be Unicode. Unicode is stored in two formats: UTF-8 and UTF-16. UTF-16 is an encoding system used by several platforms...
From Daniel Lemire's Blog
Simpler and faster parsing code with std::views::split
Parsing text files is often confusing irrespective of your programming language. It can also be surprising slow. As an example, let us consider the following problem...
From Daniel Lemire's Blog
Accessing the attributes of a struct in C++ as array elements?
In C++, it might be reasonable to represent a URL using a class or a struct made of several strings, like so: struct basic { std::string protocol; std::string username...
From Daniel Lemire's Blog
Data structures as jigs for programmers (Go edition)
A data structure in programming is a specific way of organizing and storing data in a computer so that it can be accessed and used efficiently. In woodworking or...
From Daniel Lemire's Blog
Parsing floats at over a gigabyte per second in C#
A few years ago, we wrote csFastFloat, a C# library to parse floating-point numbers faster. Given the string “3.1416”, it computes the binary value 3.1416. TheContinue...
From Daniel Lemire's Blog
Graduate degrees are overrated
Though I have many brilliant graduate students, I love working with undergraduate students. And I am not at all sure that you should favor people with graduateContinue...
From Daniel Lemire's Blog
Having fun with modern C++
Recent versions of the C++ language (C++20 and C++23) may allow you to change drastically how you program in C++. I want to provide some fun examples. Thanks to...
From Daniel Lemire's Blog
How fast can you parse a CSV file in C#?
We often store large datasets using comma-separated-value (CSV) files. The format is simple enough, each line of a text file is made of several values separated...
From Daniel Lemire's Blog
Table lookups are efficient
When optimizing small functions, I often rely on a table lookup: I replace the actual computation with table of precomputed values. It is often surprisingly efficient...
From Daniel Lemire's Blog
From software to reality?
Both the Physics and Chemistry Nobel prizes were awarded to computer scientists in 2024. Computer scientists are emerging as leading figures in the natural sciences...
From Daniel Lemire's Blog
Geoffrey Hinton, the Godfather of Deep Learning, wins Nobel Prize in Physics!
So… in 2024, the Physics Nobel prize was awarded to a Computer Scientist. Is Physics out of ideas? The Nobel Committee just gave a Physics award to a COMPUTER SCIENTIST...
From Daniel Lemire's Blog
Iterating through matched characters in modern C++: views::filter and coroutine
Consider the following problem. You want to iterate through the characters of a strings and find only those matching some criteria. For example, you might wantContinue...
From Daniel Lemire's Blog
It is never too later to write your own C/C++ command-line utilities
Recently, I received an email from an engineer at a prominent company who shared how he managed to save his employer tens of thousands of dollars annually by developing...
From Daniel Lemire's Blog
Replace strings by views when you can
C++ programmers tend to represent strings using the std::string class. Though the implementation might vary, each instance of an std::string might use 32 bytes....
From Daniel Lemire's Blog
Compressing floating-point numbers quickly by converting them to brain floats
We sometimes have to work a large quantity of floating-point numbers. This volume can be detrimental to performance. Thus we often want to compress these numbers...
From Daniel Lemire's Blog
Parsing tiny and very large floating-point values: a programming-language comparison
Most programming languages support floating-point numbers. You typically have the ability to turn a string into a floating-point number. E.g., “3.1416” could be...
From Daniel Lemire's Blog