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Time in C++: std::chrono::high_resolution_clock: Myths and Realities -- Sandor Dargo

By Blog Staff | Jan 2, 2026 10:21 AM | Tags: None

SANDOR_DARGO_ROUND.JPGstd::chrono::high_resolution_clock sounds like the obvious choice when you care about precision, but its name hides some important caveats. In this article, we’ll demystify what “high resolution” really means in <chrono>, why this clock is often just an alias, and when—if ever—it’s actually the right tool to use.

Time in C++: std::chrono::high_resolution_clock - Myths and Realities

by Sandor Dargo

From the article:

If there’s one clock in <chrono> that causes the most confusion, it’s std::chrono::high_resolution_clock. The name sounds too tempting — who wouldn’t want “the highest resolution”? But like many things in C++, the details matter.

In the earlier parts of this series, we looked at system_clock as the wall-clock time source, and at steady_clock as the reliable choice for measuring intervals. This time, we’ll tackle the so-called “high-resolution” clock, separate fact from myth, and see why it’s not always the right choice — even when you think you need precision.

What “high resolution” actually means

A clock’s resolution (or precision) is the granularity of its tick period — i.e., the smallest representable step in time for that clock’s time_point. In <chrono> it’s exposed via Clock::period, a std::ratio.

Notice an important difference. I didn’t mention accuracy, only precision. A clock might represent nanoseconds, but still be inaccurate due to hardware or OS scheduling. A higher resolution doesn’t necessarily mean better measurement. For timing, stability and monotonicity matter much more than how fine-grained the tick is.

Coroutines – A Deep Dive -- Quasar Chunawala

By Blog Staff | Dec 30, 2025 10:17 AM | Tags: None

logo.pngCoroutines are powerful but require some boilerplate code. Quasar Chunawala explains what you need to implement to get coroutines working.

Coroutines – A Deep Dive

by Quasar Chunawala

From the article:

The following code is the simplest implementation of a coroutine:

  #include <coroutine>
  void coro_func(){
    co_return;
  }
  int main(){
    coro_func();
  }

Our first coroutine will just return nothing. It will not do anything else. Sadly, the preceding code is too simple for a functional coroutine and it will not compile. When compiling with gcc 15.2, we get the error shown in Figure 1.

<source>: In function 'void coro_func()':
<source>:4:5: error: unable to find the promise type for this coroutine
    4 |     co_return;
      |     ^~~~~~~~~
Figure 1

Looking at C++ reference, we see that the return type of a coroutine must define a type named promise_type.

Concurrency Flavours -- Lucian Radu Teodorescu

By Blog Staff | Dec 26, 2025 10:14 AM | Tags: None

logo.pngConcurrency has many different approaches. Lucian Radu Teodorescu clarifies terms, showing how different approaches solve different problems.

Concurrency Flavours

by Lucian Radu Teodorescu

From the article:

Most engineers today use concurrency – often without a clear understanding of what it is, why it’s needed, or which flavour they’re dealing with. The vocabulary around concurrency is rich but muddled. Terms like parallelism, multithreading, asynchrony, reactive programming, and structured concurrency are regularly conflated – even in technical discussions.

This confusion isn’t just semantic – it leads to real-world consequences. If the goal behind using concurrency is unclear, the result is often poor concurrency – brittle code, wasted resources, or systems that are needlessly hard to reason about. Choosing the right concurrency strategy requires more than knowing a framework or following a pattern – it requires understanding what kind of complexity you’re introducing, and why.

To help clarify this complexity, the article aims to map out some of the main flavours of concurrency. Rather than defining terms rigidly, we’ll explore the motivations behind them – and the distinct mindsets they evoke. While this article includes a few C++ code examples (using features to be added in C++26), its focus is conceptual – distinguishing between the flavours of concurrency. Our goal is to refine the reader’s taste for concurrency.

Finding the Next Code Point in Unicode Strings -- Giovanni Dicanio

By Giovanni Dicanio | Dec 24, 2025 03:12 PM | Tags: None

With ASCII, it's very simple to find the next character in a string: you can just increment an index (i++) or char pointer (pch++). But what happens when you have Unicode strings to process?

Finding the Next Unicode Code Point in Strings: UTF-8 vs. UTF-16

by Giovanni Dicanio

From the article:

Both UTF-16 and UTF-8 are variable-length encodings. In particular, UTF-8 encodes each valid Unicode code point using one to four 8-bit byte units. On the other hand, UTF-16 is somewhat simpler: In fact, Unicode code points are encoded in UTF-16 using just one or two 16-bit code units.

(...) The functions have the following prototypes:

// Returns the next Unicode code point and number of bytes consumed.
// Throws std::out_of_range if index is out of bounds or string ends prematurely.
// Throws std::invalid_argument on invalid UTF-8 sequence.
[[nodiscard]] std::pair<char32_t, size_t> NextCodePointUtf8(
    const std::string& str,
    size_t index
);

// Returns the next Unicode code point and the number of UTF-16 code units consumed.
// Throws std::out_of_range if index is out of bounds or string ends prematurely.
// Throws std::invalid_argument on invalid UTF-16 sequence.
[[nodiscard]] std::pair<char32_t, size_t> NextCodePointUtf16(
    const std::wstring& input,
    size_t index
);

 

Hardening the C++ Standard Library at massive scale -- Dionne, Rebert, Shavrick, and Varlamov

By Blog Staff | Dec 24, 2025 10:11 AM | Tags: None

acmqueue_logo.gifMemory-safety vulnerabilities remain one of the most persistent and costly risks in large-scale C++ systems, even in well-tested production code. This article explores how hardening the C++ Standard Library—specifically LLVM’s libc++—can deliver meaningful security and reliability gains at massive scale with minimal performance overhead.

Practical Security in Production: Hardening the C++ Standard Library at massive scale

by Louis Dionne, Alex Rebert, Max Shavrick, and Konstantin Varlamov

From the article:

Over the past few years there has been a lot of talk about memory-safety vulnerabilities, and rightly so—attackers continue to take advantage of them to achieve their objectives. Aside from security, memory unsafety can be the cause of reliability issues and is notoriously expensive to debug. Considering the billions of lines of C++ code in production today, we need to do what we can to make C++ measurably safer over the next few years with as low of an adoption barrier as possible.

In 2019, Alex Gaynor, a security expert and one of the leading voices in memory safety, wrote a piece titled "Modern C++ Won't Save Us," where he gave examples of foundational types such as std::optional that were unsafe in the idiomatic use cases. What happens when these unsafe types are used beyond their contract? Well, you guessed it: undefined behavior. The std::optional type isn't the only one to behave like this. If you look at how this compares with modern languages, you can see that C++ is the outlier.

So, what's to be done? Possibly one of the best places to start today is by improving our standard libraries. They provide the baseline "vocabulary types" for developers—and if they're not safe, it will be tough to build safety around them. The std::optional type is only one of many vocabulary types in the C++ Standard Library that aren't safe by default today. Given the current state, it seems mostly clear that the first step should be hardening our standard library, and in our case, this was LLVM's libc++.

Qt acquires I.A.R.

By Ville Voutilainen | Dec 23, 2025 03:08 PM | Tags: None

Qt completes the recommended public cash offer to the shareholders of I.A.R. Systems Group

From the article:

On 4 July 2025, Qt Group Plc's ("Qt Group") wholly owned subsidiary The Qt Company Ltd ("The Qt Company" and together with Qt Group, "Qt"), announced a recommended public cash offer to the shareholders of class B shares (the "Shares" or, individually, a "Share") in I.A.R. Systems Group AB (publ) ("IAR"), to tender all their Shares at a price of SEK 180 in cash per Share (the "Offer"). The Shares in IAR are traded on Nasdaq Stockholm, Mid Cap. An offer document relating to the Offer was published on 15 August 2025.

At the end of the acceptance period on 10 October 2025, the Offer had been accepted by shareholders with a total of 12,037,848 Shares in IAR, corresponding to 94.49 per cent of the outstanding shares and votes in IAR.[1] As a result, The Qt Company controls in total 12,037,848 Shares in IAR, corresponding to 94.49 per cent of the outstanding shares and votes in IAR.[2]

The Qt Company has decided to complete the Offer. All conditions are satisfied or have been waived. Settlement for Shares tendered in the Offer during the initial acceptance period will be initiated on or around 17 October 2025.

 

Event-driven flows -- Andrzej Krzemieński

By Blog Staff | Dec 22, 2025 10:06 AM | Tags: None

2025-12-19_10-06-35.pngThis post is in response to two claims about coroutines: 1) Their reference function parameters may become dangling too easily, and 2) They are indistinguishable from regular functions from the declaration alone.

Event-driven flows

by Andrzej Krzemieński

From the article:

A canonical example of an event-driven flow is the handling of signals in C. Signals will be risen at unpredictable points in time, so rather than actively checking for them, we define a callback and associate it with the indicated signal:

signal(SIGINT, on_interrupt);

 

After having performed this association, we move on to doing other things. It is the implementation (system, or parts of the program we do not write) that will make sure to invoke the callback when the signal is risen (if at all). We can illustrate it with a diagram:

 

Converting Between Unicode UTF-16 and UTF-8 in Windows C++ Code -- Giovanni Dicanio

By Giovanni Dicanio | Dec 19, 2025 03:12 PM | Tags: None

Very often the need arises in Windows C++ programming to convert text between Unicode UTF-16 (which historically has been the native Unicode encoding used by Windows APIs) and UTF-8 (which is the de facto standard for sending text across the Internet and exchanging text between different platforms).

Converting Between Unicode UTF-16 and UTF-8 in Windows C++ Code

by Giovanni Dicanio

From the article:

A detailed discussion on how to convert C++ strings between Unicode UTF-16 and UTF-8 in C++ code using Windows APIs like WideCharToMultiByte, and STL strings and string views.