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C++ programmer's guide to undefined behavior: part 4 of 11

By Andrey Karpov | Aug 23, 2024 07:45 AM | Tags: undefined behavior ub tuples lifetime extension lifetime lambda function

Your attention is invited to the fourth part of an e-book on undefined behavior. This is not a textbook, as it's intended for those who are already familiar with C++ programming. It's a kind of C++ programmer's guide to undefined behavior and to its most secret and exotic corners. The book was written by Dmitry Sviridkin and edited by Andrey Karpov.

C++ programmer's guide to undefined behavior: part 4 of 11

by Dmitry Sviridkin

From the article:

In the C++98, the committee made a terrible decision that seemed reasonable at the time. They created a specialization for std::vector<bool>. Normally, sizeof(bool) == sizeof(char), but one bit is enough for bool. However, 99.99% of all possible platforms can't address memory one bit at a time. Let's pack bits in vector<bool> and store CHAR_BIT (usually 8) boolean values in one byte (char) for more efficient memory utilization. As a result, one needs to work with std::vector<bool> in a very special way...

C++ programmer's guide to undefined behavior: part 3 of 11

By Andrey Karpov | Aug 5, 2024 05:26 AM | Tags: undefined behavior ub lifetime dangling references

Your attention is invited to the third part of an e-book on undefined behavior. This is not a textbook, as it's intended for those who are already familiar with C++ programming. It's a kind of C++ programmer's guide to undefined behavior and to its most secret and exotic corners. The book was written by Dmitry Sviridkin and edited by Andrey Karpov.

C++ programmer's guide to undefined behavior: part 3 of 11

by Dmitry Sviridkin

From the article:

This program, built by GCC 10.1, -std=c++20 -O3, doesn't crash, but it doesn't output anything either. If we take GCC 14.1 and the same keys, we suddenly get "helloworld" in the output. It's old but gold undefined behavior.

Lifetime extension of temporary objects in C++: common recommendations and pitfalls

By Andrey Karpov | Nov 2, 2022 01:39 AM | Tags: temporary objects lifetime

After reading this article, you will learn the following: ways to extend the lifetime of a temporary object in C++, various tips and tricks; pitfalls of the lifetime extension that a C++ programmer may face.

Lifetime extension of temporary objects in C++: common recommendations and pitfalls

by Evgeny Neruchek

From the article:

You can extend the lifetime of a temporary array by referencing one of its elements. C++ has a special mechanism for this. But I would recommend you using it only in the disputes with your co-workers (and maybe in metaprogramming with the old C++ standards), since this mechanism is not so easy-to-use. However, using this mechanism does not result in dangling references, and the lifetime of the temporary array is extended to the lifetime of the reference to its element.