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Inside STL: The string -- Raymond Chen

By Blog Staff | Sep 4, 2023 03:07 PM | Tags: None

Raymond Chen You might think that a std::string (and all of its friends in the std::basic_string family) are basically a vector of characters internally. But strings are organized differently due to specific optimizations permitted for strings but not for vectors.

Inside STL: The string

By Raymond Chen

From the article:

The starting point for a std::basic_string is this:¹
template<typename T>
struct basic_string
{
    T* ptr;
    size_t size;
    size_t capacity;
};
The ptr is a pointer to the beginning of the string contents.

The size is the number of characters in the string, not including the null terminator.

The capacity is the string capacity, not including the null terminator.

The picture for this simplified version is as follows:

CppCon 2023 A Long Journey of Changing std::sort Implementation at Scale -- Danila Kutenin

By Blog Staff | Sep 4, 2023 02:26 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 some upcoming talks that you will be able to attend this year. Here’s another CppCon future talk we hope you will enjoy – and register today for CppCon 2023!

A Long Journey of Changing std::sort Implementation at Scale

Monday, October 2 • 14:00 - 15:00

by Danila Kutenin

Summary of the talk:

Sorting algorithms have been improving for almost 50 years now with claims of better efficiency and various properties but the question of adopting a new one at scale is often left behind. At Google we replaced std::sort in the LLVM libc++ library to test it for hundreds of thousand calls. We faced many challenges which we had been fixing for 2 years including golden tests, efficiency problems, undefined behavior and broken production. In this talk we want to cover issues on how we improved debugging, benchmarking, how much better a new implementation was compared to the old one and what we have learned on this journey of improved sorting.

CppCon 2023 Back to Basics: Functions -- Mike Shah

By Blog Staff | Sep 3, 2023 02:23 PM | Tags: None

Back to Basics: Functions

Monday, October 2 • 14:00 - 15:00

by Mike Shah

Summary of the talk:

Functions are one of the first things programmers learn, granting you the ultimate power to 'resuse' code and build modular programs. In this talk, we are going to provide an overview of functions from the start to the end, on the various powers that are given to us from the ground up. Consider this talk your one stop for learning all of the great things about functions!

We'll start with a basic function example, identifying the function signature and basic abilities of a function. Then we are going to view this function again from the perspective of assembly (using compiler explorer) to show you how a function is structured. From the assembly view, we will then observe that functions have addresses (they must after all!) and that we can store functions in pointers. We'll take a brief aside to show you how modern C++ also gives us the convenient std::function. Functions need not always be 'global' building blocks of our programs, the next step in our journey will be to see how we can have functions at local scope (e.g. lambda's) and how they can be used (and often times in handy ways in the STL). Ah, intrigued are you? We're not quite done! Now with building blocks such as lambda's (and related functors) we can utilize function composition to really unlock the power of functions. Towards the end of this talk, we will talk about grouping related functions (into namespaces) and as member functions in classes. Within our discussion of functions in classes, we'll touch on virtual functions, static functions, and operator overloading. We'll circle back to where we began on these topics, again showing you the assembly. At the end of this talk, you will have had FUN with functions (I couldn't resist...but you will see the complete C++ picture of functions).

CppCon 2023 Lifetime Safety in C++: Past, Present and Future -- Gabor Horvath

By Blog Staff | Sep 2, 2023 02:19 PM | Tags: None

Lifetime Safety in C++: Past, Present and Future

Monday, October 2 • 11:00 - 12:00

by Gabor Horvath

Summary of the talk:

How can we make C++ safer without sacrificing its performance and flexibility? Memory safety is a desirable property for any C++ program, but it is not easy to achieve. Recent revisions of the C++ standard rendered some unsafe code ill-formed or harmless, but there are still many gaps. Comprehensive lifetime analysis like that of Rust can help detect memory errors, but it often requires major changes to the code structure. This can be impractical, costly, and risky, especially for legacy code. This talk surveys mitigations available today that can help enhance the safety of our code. These mitigations include warnings and static analysis checks from MSVC, Clang, and GCC, dynamic analysis tools, and changes to the C++ language. It also explores some directions to further improve the safety of the language.

CppCon 2023 Expressive Compile-time Parsers -- Alon Wolf

By Blog Staff | Sep 1, 2023 02:17 PM | Tags: None

CppCon 2023 Expressive Compile-time Parsers

Monday, October 2 • 11:00 - 12:00

by Alon Wolf

Alon is a Senior Software Engineer at Medtronic specializing in 3D and computer graphics with a passion for high performance. He has developed many custom simulation and rendering engines for different platforms using modern C++. He also writes a C++ technical blog and participates in game jams.

Inside STL: The vector -- Raymond Chen

By Blog Staff | Aug 31, 2023 03:01 PM | Tags: None

The C++ language comes with a standard library, and although implementations are welcome to implement the library types in whatever manner they choose, they are constraints imposed by the standard which often force one of a small number of possible implementations.

Inside STL: The vector

By Raymond Chen

The std::vector is one of those types which is constrained to the point that there’s really only one viable implementation.

Internally, a std::vector basically looks like this:

template<typename T>
struct vector
{
    T* first;
    T* last;
    T* end;
};

The first is a pointer to the beginning of a single memory allocation that holds the vector contents.

The last is a pointer one past the end of the last valid vector element.

The end is a pointer one past the end of the last allocated memory for the vector.

The picture for this is as follows:

CppCon 2023 Customization Methods: Connecting User and Library Code -- Inbal Levi

By Blog Staff | Aug 31, 2023 11:15 AM | Tags: None

Customization Methods: Connecting User and Library Code

Monday, October 2 • 11:00am - 12:00pm

by Inbal Levi

Summary of the talk:

The interface between a library and its users is a major design consideration for every developer, and has been evolving greatly over C++’s lifetime. In this talk we will go over different methods for connecting generic library code with user-side specific code, commonly known as Customization Points. We will cover the benefits and downsides of different methods (including CTS, ADL, Concepts, CTOs, and the latest to be considered - tag_invoke), and present future directions for these mechanisms.

At the end of the talk, you’ll be familiar with the terminology and developments in this field, including the ones planned for C++23 and C++26.

CppCon 2023 Back to Basics: Templates -- Rainer Grimm

By Blog Staff | Aug 30, 2023 11:08 AM | Tags: None

Back to Basics: Templates

Monday, October 2 • 11:00am - 12:00pm

by Rainer Grimm

Summary of the talk:

The future of C++ speaks templates. Therefore, a professional C++ programmer must know the basics of templates. In this talk, I will provide this basic knowledge about function and class templates, template arguments and parameters, and template specialization. Additionally, thanks to C++ Insights, I can further deepen your intuition about templates.

Inside STL: The Pair and The Compressed Pair -- Raymond Chen

By Blog Staff | Aug 29, 2023 02:57 PM | Tags: None

The C++ language comes with a standard library. When you’re debugging your C++ code, you may have to go digging inside the implementation to extract information from crash dumps. This mini-series is going to look at how various C++ standard library types are implemented by the three major implementations (clang, gcc, and msvc).

Inside STL: The Pair and The Compressed Pair

By Raymond Chen

From the article:

The C++ language comes with a standard library. When you’re debugging your C++ code, you may have to go digging inside the implementation to extract information from crash dumps. This mini-series is going to look at how various C++ standard library types are implemented by the three major implementations (clang, gcc, and msvc).

We’ll start with the lowly std::pair. Its definition is quite simple.
template<typename T1, typename T2>
struct pair
{
    T1 first;
    T2 second;
};
The names of the members of std::pair are required by the C++ language standard, so you don’t see any variation here. Here’s how it looks in the Windows debugger:
0:000> ?? t
struct std::pair<int,int>
   +0x000 first            : 0n42
   +0x004 second           : 0n99

CppCon 2023 Delivering Safe C++ -- Bjarne Stroustrup

By Blog Staff | Aug 29, 2023 07:30 AM | Tags: None

Delivering Safe C++

Monday, October 2 • 8:45am - 10:30am

by Bjarne Stroustrup

Summary of the talk:

Type safety was one of the key initial C++ design ideals. We have evolved C++ to the point where we can write C++ with no violations of the type system, no resource leaks, no memory corruption, no garbage collector, no limitation of expressiveness or performance degradation compared to well-written modern C++.

We face three major challenges: To define what “safe” means in the context of various C++ uses, to guarantee such safety where guarantees are needed, and to get developers to write such verified safe code.

I outline an approach based on safety profiles to address these challenges, describe an approach to eliminate dangling pointers, and suggest how to eliminate all dangling pointers and all range errors. My aim for key applications is verified type-and-resource-safe C++. An emphasis is on minimizing costly run-time checks through the use of abstractions. I see the current emphasis on safety as an opportunity to complete one aspect of C++’s fundamental aims in real-world code.