strlen() の深淵 - Qiita
あらまし strlen() という関数がある。御存知の通り、文字列の長さを算出する標準 C ライブラリの関数だ。 やってることは単純で、例えば以下のように実装できる。 size_t strlen_simple(const char* str) { const char* p = str; while (*p) ++p; return size_t(p - str); } '\0' が見つかるまでポインタを進め、初期位置との差分を返すだけだ。これで機能的には std::strlen() と同等である。 では、速度的にはどうだろう？適当にベンチマークを書いて MSVC 2022 でコンパイル＆実行するとこうなった。
Nix Based C++ Workflow From Scratch | The Farming Coders
If you are like me, you have probably already suffered a lot from having your poject depend on libraries installed in your system (e.g. libraries installed with apt install). The down side of having system-wide dependencies is multi-fold but it can be summarized as simple as: It is not reproducible on another machine or another system. It can potentially introduce serious conflicts between your mu
C++のラムダで再帰する - koturnの日記
はじめに C++において，ラムダで再帰したいと考えることはたまにある． この記事ではラムダで再帰する手法をいくつか紹介する． 例として扱う再帰関数はフィボナッチ数列の関数（もっとも単純な実装）とする． int fib(int n) noexcept { return n < 2 ? n : (fib(n - 1) + fib(n - 2)); } 生成コード ラムダで再帰を行いたいと考えるのは変数のキャプチャをしつつ再帰をしたい場面であると思う． 例えば，メモ化再帰を行うと考えた場合， グローバル変数としてメモ化配列を用意する メモ化再帰用のクラスを用意する（メンバにメモ化配列を用意する） 再帰関数の引数にメモ化配列を与える といった方法が考えられるが，グローバル変数や専用のクラス定義が必要であり，あまりやりたくない． 引数にメモ化配列を与えるとなると，全ての再帰呼び出し箇所の記述が冗長に
A Universal I/O Abstraction for C++ | cor3ntin
January 31, 2020 A Universal I/O Abstraction for C++ This article is the sequel to A Universal Async Abstraction for C++, in which I talk about the Executor proposal targeting C++23. Quite a bit happened since then. SG-11, the study group charged of all things concurrency and parallelism made forward progress and sent the proposal to LEWG - with the hope of landing a future revision in the C++23 d
All C++20 core language features with examples
Introduction The story behind this article is very simple, I wanted to learn about new C++20 language features and to have a brief summary for all of them on a single page. So, I decided to read all proposals and create this “cheat sheet” that explains and demonstrates each feature. This is not a “best practices” kind of article, it serves only demonstrational purpose. Most examples were inspired
Summary of C/C++ integer rules
This is my own collection of hard-earned knowledge about how integers work in C/C++, and how to use them carefully and correctly. In this article, I try to strike a balance between brevity (easing the reader) and completeness (providing absolute correctness and extensive detail). Whenever I read or write C/C++ code, I need to recall and apply these rules in many situations, such as: Choosing an ap
Fun with conversion-operator name lookup
As of this writing (but perhaps not for very much longer!) the four mainstream compilers on Godbolt Compiler Explorer give four different answers for this simple C++ program: struct A { using T = T1; using U = U1; operator U1 T1::*(); operator U1 T2::*(); operator U2 T1::*(); operator U2 T2::*(); }; inline auto which(U1 T1::*) { return "gcc"; } inline auto which(U1 T2::*) { return "icc"; } inline
［C++］モジュールにおける所有権モデル - 地面を見下ろす少年の足蹴にされる私
モジュールにおける所有権とは、名前付きモジュールに属しているエンティティの名前に関する所有権の事で、次のようなコードがどう振舞うかを決定するものです。 /// moduleA.ixx export module moduleA; export int munge(int a, int b) { return a + b; } /// moduleB.ixx export module moduleB; export int munge(int a, int b) { return a - b; } /// libA.h int libA_munge(int a, int b); /// libA.cpp #include "libA.h" import moduleA; int libA_munge(int a, int b) { return munge(a, b); } /// mai
GitHub - shafik/determine_c_or_cpp: Determine programatically C from C++ as well as various versions
わかりにくかったバグとの戦いの記録 - Qiita
// clang++ -std=c++17 -O3 -Wall -lpthread && ./a.out 10000 #include <chrono> #include <condition_variable> #include <iostream> #include <mutex> #include <thread> using namespace std; using namespace std::chrono_literals; class foo { thread th_; mutex mutex_; condition_variable cv_; public: void notify() { cv_.notify_all(); } foo() : th_([this]() { unique_lock<mutex> lock(mutex_); if (cv_status::no
C++11 thread-safe queue
A project I'm working on uses multiple threads to do work on a collection of files. Each thread can add files to the list of files to be processed, so I put together (what I thought was) a thread-safe queue. Relevant portions follow: // qMutex is a std::mutex intended to guard the queue // populatedNotifier is a std::condition_variable intended to // notify waiting threads of a new item in the que
abseil / C++ Tips of the Week
Background: About five years ago, within Google we started publishing a series of C++ tips, about once a week, that became known as the “C++ Tips of the Week” (TotW). They became wildly successful, and we are still publishing them to this day (indicating that a language as rich as C++ will not deplete us of topics anytime soon). Not only do we discuss the finer points of the language, but in true
リリース、障害情報などのサービスのお知らせ
最新の人気エントリーの配信
j次のブックマーク
k前のブックマーク
lあとで読む
eコメント一覧を開く
oページを開く
プログラム解析入門、もしくはC/C++を安全に書くのが難しすぎる話
301 Moved Permanently
Learn Contemporary C++ | Concise&Visual Examples
https://cppnow.digital-medium.co.uk/wp-content/uploads/2021/05/2021-05-04_-The-Complete-Guide-to-return-x-1.pdf
Convert Binary File into Object File for C/C++
INT32-C. Ensure that operations on signed integers do not result in overflow - SEI CERT C Coding Standard - Confluence
ゲーム開発者のための C++11～C++20, 将来の C++ の展望 - CEDEC2020 - Speaker Deck
Stopping long-sleep threads