Write More C++ Code Thanks to constexpr -- Andreas Fertig

By Blog Staff | Jan 6, 2025 11:15 AM | Tags: None

Since its introduction, constexpr in C++ has evolved significantly, offering powerful ways to optimize code at compile-time. This article shares a real-world story of using constexpr to dramatically reduce memory usage and code size in an embedded system, showcasing its potential to improve both performance and efficiency.

Write More C++ Code Thanks to constexpr

by Andreas Fertig

From the article:

I'm a big fan of constexpr and am not alone. Jason Turner is also very vocal, having coined the term "constexpr all the things".

Well, demonstrating the powers of constexpr is nonetheless something difficult. I know that from my training classes and various consulting contracts. Today, I'd like to share a story from back in time when a customer hired me to consult. They did develop an embedded system and ran out of memory. Not during run-time, but before. The features they wanted to put in the chip were too big in code size and somewhat RAM.

Initial constexpr-free example

They used a class I've seen a couple of times in embedded systems with some variations. A string brings its memory picky-back.

It’s just ‘,’ – The Comma Operator -- Coral Kashri

By Blog Staff | Jan 3, 2025 11:07 AM | Tags: None

We all know that every ‘,’ matters in this language, so I decided to talk directly about that character today. So, how much impact can be for such a small little character?

It’s just ‘,’ – The Comma Operator

by Coral Kashri

From the article:

This operator comes from C, where it tells the compiler to evaluate all the expressions (left to right) and to return the result of the latest evaluated expression. For example:

     int a, b;

     a = 5, b = 4, b += a, ++a, std::cout << b << " " << a; // Prints 9 6

Another example of that operator usage is as follows:

     for (size_t i = 0, k = 500; i < 10; ++i, ++k) { /*...*/ }

We can see this operator in action in the third section of the for statement. It evaluates the ++i and then evaluates ++k.