How To Check If A Pointer Is In A Range Of Memory -- Raymond Chen

By Blog Staff | May 24, 2023 08:09 AM | Tags: None

C language was defined to cover a large range of computer architectures, including many which would be considered museum relics today. It therefore takes a very conservative view of what is permitted, so that it remains possible to write C programs for those ancient systems. (Which weren’t quite so ancient at the time.)

How To Check If A Pointer Is In A Range Of Memory

by Raymond Chen

From the article:

Suppose you have a range of memory described by two variables, say,

byte* regionStart;
size_t regionSize;

And suppose you want to check whether a pointers lies within that region. You might be tempted to write

if (p >= regionStart && p < regionStart + regionSize)

but is this actually guaranteed according to the standard?

2023-05 Mailing Available

By Administrator | May 23, 2023 08:51 AM | Tags: None

The 2023-05 mailing of new standards papers is now available.

CppCon 2022 10 Tips for Cleaner C++ 20 Code -- David Sackstein

By Blog Staff | May 23, 2023 06:21 AM | Tags: None

Registration is now open for CppCon 2023! The conference starts on October 1 and will be held in person in Aurora, CO. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from last year's conference. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2023!

10 Tips for Cleaner C++ 20 Code

by David Sackstein

Summary of the talk:

The objective of this session is to provide guidelines and tips that will help the audience write readable, testable and extensible code with modern C++.

One of the greatest challenges we face, as programmers, is to make sure that our code can be understood and used by our colleagues - and not only by the compiler.

As the complexity of C++ increases, the compiler is able to deduce and optimize more of our code, but often at the cost of making it more obscure for our colleagues. Code that is difficult to read is difficult to test, to maintain and to extend.

In the session, I propose to help the audience understand the core problems that we introduce as our programming becomes more advanced, and how we can avoid them. The main part of the session will discuss some fairly complex and advanced C++ code which is difficult to understand. I will then demonstrate 10 easily applicable tips to make it easier to understand and to test. The benefits will be clearly evident.

There will also be a short discussion with the audience to increase the confidence that the guidelines and the tips are readily applicable in their own diverse projects.

More than a rehash – Joaquín M. López in Madrid at Using std::cpp

By Jordi Mon Companys | May 23, 2023 03:35 AM | Tags: community

In this talk, Joaquín will invite you to look under boost::unordered_flat_map's hood with him and learn about this container's data structure, its key design elements and how it compares with other top-performance C++ hashmaps both in theory and in practice.

More than a rehash – Joaquín M. López in Madrid at Using std::cpp
by Joaquín M. López

From the talk:

Boost 1.81 (Dec 2022) released boost::unordered_flat_map, a hashmap (unordered associative container in C++ parlance) that relies on open addressing and SIMD techniques to provide extremely high performance. In this talk, Joaquín will invite you to look under boost::unordered_flat_map's hood with him and learn about this container's data structure, its key design elements and how it compares with other top-performance C++ hashmaps both in theory and in practice. The talk finishes with a teaser on concurrent hashmaps arriving as part of your Boost update later this year. Deck and note can be found here. 

Why is std::hardware_destructive_interference_size a Compile-time Constant ... -- Raymond Chen

By Blog Staff | May 22, 2023 03:03 PM | Tags: None

C++17 added a new compile time constant std::hardware_destructive_interference_size which tells you (basically) the size of a cache line. The purpose of this is to allow you to lay out your structures in a way that avoids false sharing.

Why is std::hardware_destructive_interference_size a Compile-time Constant Instead of a Run-time Value?

by Raymond Chen

From the article:

C++17 added a new compile time constant std::hardware_destructive_interference_size which tells you (basically) the size of a cache line. The purpose of this is to allow you to lay out your structures in a way that avoids false sharing.¹

But how does the compiler know what the cache line size will be of the CPU the program will eventually be run on? Shouldn’t this be a run-time value instead of a compile-time value?

Well yes, the actual size of the cache line isn’t know until run-time, because it is only then that the program meets a CPU. But really, you want this to be a ...

CppCon 2022 Can C++ be 10x Simpler > Safer? -- Herb Sutter

By Blog Staff | May 21, 2023 09:46 AM | Tags: None

Registration is now open for CppCon 2023! The conference starts on October 1 and will be held in person in Aurora, CO. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from last year's conference. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2023!

Can C++ be 10x Simpler & Safer? (Simplifying C++ #9 of N)

by Herb Sutter

Summary of the talk:

Since CppCon 2015, all of Herb’s talks have been about ways to evolve C++ to make it simpler, safer, and more toolable. Every release of ISO C++ has already been making regular incremental “10%” improvements in these areas. But what are the fundamental factors that limit our rate of improvement, and what would it take to make greater progress? Like every year, Herb’s talk will explore selected current pain points and describe experimental ideas to address them that might someday contribute toward C++’s long-term evolution.

Reactor -- Rainer Grimm

By Blog Staff | May 19, 2023 02:58 PM | Tags: None

Event-driven applications, such as GUIs or servers, often apply the architecture pattern Reactor. A Reactor can accept multiple requests simultaneously and distribute them to different handlers.

Reactor

by Rainer Grimm

From the article:

The Reactor Pattern is an event-driven framework to concurrently demultiplex and dispatch service requests to various service providers. The requests are processed synchronously.

Problem

A server should

• be extendable to support new or improved services
• be performant, stable, and scalable
• answer several client requests simultaneously

The application should be hidden from multi-threading and synchronization challenges

Solution

• Each supported service is encapsulated in a handler
• The handlers are registered within the Reactor
• The Reactor uses an event demultiplexer to wait synchronously on all incoming events
• When the Reactor is notified, it dispatches the service request to the specific handler

CppCon 2022 Best Practices Every C++ Programmer Needs to Follow -- Oz Syed

By Blog Staff | May 18, 2023 03:42 PM | Tags: None

Registration is now open for CppCon 2023! The conference starts on October 1 and will be held in person in Aurora, CO. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from last year's conference. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2023!

Lightning Talk: Best Practices Every C++ Programmer Needs to Follow

by Oz Syed

Summary of the talk:

In this session, learn some of the best practices that every C++ programmer needs to ensure successful completion of a project. Learn tips and tricks to speed up your workflow, prevent errors and improve performance.

Q&A - C++ Initialization -- Bartlomiej Filipek

By Blog Staff | May 17, 2023 09:43 AM | Tags: None

Last time I showed a couple of questions about initialization. Try them here if you haven’t already. In this article, I’ll show you the answers and add more notes about initialization in C++.

Q&A - C++ Initialization

by Bartlomiej Filipek

From the article:

Will this code work in C++11?

struct User { std::string name = "unknown"; unsigned age { 0 }; };
User u { "John", 101 };

1. Yes, the code compiles in C++11 mode.
2. The code compiles starting with C++14 mode.
3. The code doesn’t compile even in C++20.

CppCon 2022 C++ in Constrained Environments -- Bjarne Stroustrup

By Blog Staff | May 16, 2023 01:37 PM | Tags: None

Registration is now open for CppCon 2023! The conference starts on October 1 and will be held in person in Aurora, CO. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from last year's conference. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2023!

C++ in Constrained Environments

by Bjarne Stroustrup

Summary of the talk:

C++ is widely used in constrained and/or critical applications and infrastructure components. How do we manage to use a large multi-purpose language in such environments? How can we better use facilities and techniques from modern C++ (C++11, C++14, C++17, C++20, and beyond)? The best answer is not “use only facilities available in C and C++ in 1985.”

This talk focuses on a top-down approach to achieve simplicity, maintainability, performance, and various forms of safety. It touches upon the C++ Core Guidelines, compile-time computation, type-and-resource safety, type deduction, the span and chrono standard libraries, and error handling.