Questions tagged [c++20]
Code that is written to the 2020 version of the C++ standard. Use in conjunction with the 'c++' tag.
215
questions
2
votes
2
answers
48
views
First contact with C++ - Graphics Library
I am trying to learn C++ by writing a basic graphics library; undergrad-toy-project level.
I am trying to write modern C++ (C++ 20 standard), but avoiding features that are not well supported by my ...
- 781
7
votes
1
answer
86
views
Improving the speed of an MD5 implementation from scratch in C++
I wrote an implementation of the MD5 hashing algorithm from scratch in C++, following the original RFC: https://www.ietf.org/rfc/rfc1321.txt . It works as expected, and the outputs match all the test ...
5
votes
2
answers
919
views
Find the best couple of an array in 1.5 seconds
I faced this exercise.
Given a sequence \$S\$ (\$2 <= |S| <= 10^6\$) of numbers (\$1 <= S_x <= 10^7\$), determine \$max(abs(S_i - S_j) + abs(i -j))\$.
Here is the solution I found:
...
- 53
3
votes
2
answers
114
views
Goats up hills II: revenge of the goat
This is a continuation of Goat racing up a hill (C++ hiring take-home) . This is an interview take-home challenge that has been translated to avoid compromising the company's question.
Problem ...
- 53.5k
5
votes
1
answer
58
views
Character source with lookahead for lexer
I've been out of the C++ game for a few years and I'm trying to knock the rust off by implementing a programming language. This Source interface is used to read ...
- 3,261
12
votes
3
answers
4k
views
Goat racing up a hill (C++ hiring take-home)
This is an interview take-home challenge that has been translated to avoid compromising the company's question.
Problem statement
You are a goat that needs to race up a hill. Designated waypoint rocks ...
- 53.5k
5
votes
1
answer
85
views
Executing a Bash script from C++
I am trying to execute a Bash command, get the pid, read the (error) output and optionally pass input.
I am still quite new at C++ and I would like to know if this is a correct & safe ...
2
votes
1
answer
40
views
Ring buffer for non-trivial types
I tried to explain in detail everything there should be of concern regarding this particular implementation, and non-code body turned out quite long, scroll down if you just want to read the ...
- 21
2
votes
3
answers
101
views
Find long palindrome multiplications in modern C++
I'm a former C# programmer, updating my rusty C++98 (perhaps I should try Rust instead) to modern C++20. My main goal is to get used to C++ standard library types and algorithms.
I chose to solve a ...
- 1,025
2
votes
1
answer
80
views
Reimplementation of Diep.io in C++ with SFML and Box2D
Here's my attempt at reimplementing part of https://diep.io/, a 2D game where tanks battle with each other. The tanks are circular and they have cannons which fire bullets. The bullets can hit other ...
- 123
5
votes
5
answers
867
views
Palindrome Permutation string
I’m starting to learn C++ by doing a lot of exercises, and I need your help so I can improve,
Here is how it goes, I will try to solve an exercise and post both the ...
- 119
3
votes
2
answers
506
views
2
votes
3
answers
81
views
A constexpr, const correct matrix class with compile-time checks
I've expanded, and enhanced my matrix class which uses, aside from dynamic memory for the elements, only 3, const literals. These are rows, cols, and a ptr. The methods are all constexpr and the ...
- 173
2
votes
1
answer
73
views
A parse function for text line with fields separated by a comma with the known number and their type
I am trying to parse a line with a fixed amount of fields and known types.
...
- 23
4
votes
1
answer
94
views
C++ Binary search using SIMD
Recently I found that the binary search (std::ranges::lower_bound and std::ranges::upper_bound) is the main bottleneck in my ...
- 1,643
4
votes
3
answers
108
views
C++ B-Tree serialization/deserialization
Yesterday I wrote a serialization/deserialization for my B-Tree library.
Since the code for whole tree is too large to upload here, I'll upload only serialization/deserialization and node class ...
- 1,643
1
vote
0
answers
33
views
C++20 B-Tree v1.0 with disk file supports and perf test
I've improved my in-memory B-Tree (Link) to release a B-Tree with support for memory-mapped disk files and fixed-size allocators:
Repository: https://github.com/frozenca/BTree
Code:
...
- 1,643
3
votes
1
answer
309
views
C++ disk-file memory resource
After writing a C++ simulator for malloc() and free(), (C++ imitation of glibc malloc(), free()),
I thought: "My simulator ...
- 1,643
5
votes
2
answers
214
views
A matrix class using const members
I've long used a simple matrix class with a vector and rows/cols for the shape. But I've always disliked getters even when necessary to prevent exposing invariants. Then came c++20 which provided the ...
- 173
3
votes
1
answer
36
views
Constraining a templated method to accept any integral std::chrono::time_point
Recently I was writing a class that had overloaded read methods for various data types. One of the sets of types I wanted to handle were integral ...
- 133
1
vote
0
answers
43
views
C++ Static polymorphism at compile-time [closed]
With C++20 constraints and concepts, we are able to retrieve some information about class at compile time. Using such information in template lead to static polymorphism.
This toy code works as ...
- 163
0
votes
0
answers
26
views
UPDATE #2: Lengthening the time it takes to access files using function hooking
https://github.com/speedrun-program/load_extender
This is the previous post: UPDATE #1: Lengthening the time it takes to access files using function hooking
I came back to this to try to improve it. I'...
2
votes
2
answers
391
views
C++ Hash table, Hash function, benchmark vs std::unordered_set and std::hash
I wrote my own hash function and my own hash table.
My hash function seems to work surprisingly well!
Feel free to comment anything!
Hash function:
...
- 1,643
2
votes
1
answer
55
views
C++ Doubly linked list, including benchmark vs std::list
I wrote a rudimentary implementation of doubly linked list.
Feel free to comment anything!
...
- 1,643
2
votes
1
answer
319
views
C++20 Multi-queue Thread Pool with Work Stealing
This is a follow up to my previous post which also follows up on my first post regarding my thread pool implementation. I have since made some further changes and attempted to improve performance with ...
- 410
1
vote
1
answer
65
views
Using std::variant with std::ranges algorithms
I have some predicate objects that take some value and return the result of some criteria. (My real implementation is more complex, this is only a minimal example):
Run on Compiler Explorer
...
- 125
1
vote
1
answer
108
views
Storing different types with common base using atomic-based typeid
I'm trying to develop some kind of in-memory store for my entities. These entities are representations of the devices available on the system. There may be eg. 3 leds, 1 temp sensor, 2 engines etc. ...
- 241
2
votes
1
answer
52
views
UPDATE #1: Lengthening the time it takes to access files using function hooking
https://github.com/speedrun-program/load_extender
This is the previous post: Lengthening the time it takes to access files using function hooking
I tried adding everything from the previous post's ...
2
votes
1
answer
57
views
Lengthening the time it takes to access files using function hooking
https://github.com/speedrun-program/load_extender
This is something I made and posted here about a year ago, but I decided to remake it.
To compile this on Windows, you need to install EasyHook.
...
0
votes
1
answer
35
views
C++20 Wrapper class for an unsigned integer type and a templated derived class that codes modular arithmetic type
The context is a library to represent numbers (in this case integers) by wheighted position by radix powers for every radix R, passed as template argument. These derived types are digits of radix R, ...
- 1
1
vote
1
answer
50
views
Verified downcasting if RTTI is active
In an application that uses heavily polymorphic classes, I have often the need to downcast a pointer or a reference to the correct derived class. They should always be of the correct derived class, ...
- 188
1
vote
1
answer
115
views
C++ merge sort, logging, unit test, performance check
I wrote a merge sort implementation in C++ today in C++20 way.
...
- 1,643
21
votes
6
answers
8k
views
I created something much faster than a std::string
I've recreated std::string in a way that might be faster.
System Features:
Much faster than std::string.
Easy to use.
It was designed as part of a large database ...
1
vote
1
answer
92
views
Yet another command / event dispatcher
I'm trying to implement some kind of command dispatcher.
I've already developed some code, but I'm not sure about a few things.
My dispatcher is a simple command dispatcher, so for each command, there ...
- 241
3
votes
1
answer
200
views
Mapping between Enum <-> Enum <-> String view
I've been working on some kind of mapper that would allow me to map between types.
My objectives:
it should allow mapping between two enums
it should allow mapping enum to string_view
it should allow ...
- 241
4
votes
2
answers
308
views
C++20 Single Queue Thread Pool
This is a follow up to my previous post. I've made a number of improvements to the thread pool and corrected some bugs as well.
The most up to date version of the code is available on my Github.
I ...
- 410
4
votes
1
answer
125
views
Searching for a performance bug in a C++20 pathfinding algorithm (NBA*)
(See the next iteration.)
I have this pathfinding algorithm:
DirectedGraph.hpp
...
- 26.1k
3
votes
1
answer
49
views
checked conversion function for C++20
Similar to C++ int_cast<> function for checked casts?, but C++20, and with target type deduced from context.
The goal is to implement a runtime check that the value being converted can be ...
- 183
3
votes
1
answer
91
views
function template for string_view-to-integer conversion
I want to make the following function a function template that supports all the integral types:
...
- 293
2
votes
1
answer
50
views
6
votes
3
answers
431
views
generic implementation of median
Below is a generic implementation of the summary statistics function Median.
Discussion of efficient use of std::nth_element and ...
- 2,435
0
votes
1
answer
45
views
Class accepting data input by variable, function pointer or lambda
Background
I am writing a library that takes some data from the user and works with it. I was experimenting with ways to allow users to provide the data by the following methods:
As a (global) ...
- 103
1
vote
1
answer
113
views
Strong typing -> Named type
I'm trying to generate a strong(er) type wrapper for C++. I've seen the NamedType by Jonathan Boccara, but I want a slightly different behavior.
Ideally I would be ...
- 424
6
votes
3
answers
673
views
15
votes
2
answers
1k
views
Block-free priority lock
Background
I wanted to write an event loop that supports scheduling, but found that no implementation of priority queue that I know of supports waiting on a condition variable (the idea is that the ...
- 9,171
2
votes
1
answer
116
views
An rough implementation of `std::is_constructible`
As a challenge/fun activity/task, I have implemented my version of std::is_constructible.
Here is the source code:
...
5
votes
4
answers
2k
views
C++ basic bank money class
I am trying to create a basic money class that fits into a small console banking application I am making.
Money.h
...
- 53
2
votes
2
answers
110
views
Checking image size in C++
This is a follow-up question for 3D Inverse Discrete Cosine Transformation Implementation in C++. After checking G. Sliepen's answer, I am trying to update the part of width and height checking of <...
- 3,596
6
votes
4
answers
551
views
Nelder-Mead optimization in C++
I've implemented the Nelder-Mead optimization algorithm in C++. I found this document to be a very good explanation of how the algorithm works, but I'll try my best to explain it (with an example) ...
- 12.3k
2
votes
0
answers
68
views
invocable_traits v5
Goal: implement traits that for anything callable return its arity, return type and the argument types. Since pointers to data members are also callable, those should be handled (and be considered 0-...
