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Questions tagged [collections]

Collections APIs provide developers with a set of classes and interfaces that makes it easier to handle collections of objects.

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1answer
79 views

C++ ring buffer using some C++ 17 and coming C++ 20 std::span [on hold]

When I heard about the new Linux I/O interface io_uring I searched about the ring buffer. I then thought I may replace my safe queue which is base on C++ 11 ...
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0answers
54 views

how to implement Collection effectively in pagination

I have created pagination library in PhP and want to implement Collection. Not sure how to split this up. my repo can be found here https://github.com/shorif2000/...
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1answer
62 views

Container that holds objects of various types, and can be searched for an object convertible to a given type

I built a container that can hold objects of various types, and look up an object convertible to a given type. I wrote something about my intended use-case here: https://stackoverflow.com/questions/...
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1answer
72 views

Code to pick buckets for a list of value

In my current project, I came across a scenario where there will be two sorted list of Decimal values. Let's call them ...
5
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3answers
753 views

reverse a list of generic type

Q: Given a list, reverse the order of its elements (don't use collections). Here is my solution: ...
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1answer
86 views

transform list to array

Q: Write a method that transforms a list into an array (don't use collections or already implemented methods in lists, make your own method) I've come with this solution: ...
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2answers
1k views

IList<T> implementation

I was wondering about the possibility to create an implementation of IList<T> that is faster than List<T> using C#, ...
3
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1answer
181 views

LinkedList Swift Implementation

Linked List Implementation in Swift Swift 5.0, Xcode 10.3 I have written an implementation for a doubly linked list in Swift. As well, I decided to make the node class private and thus hidden to the ...
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2answers
92 views

A java program that gets a key-value pairs from a textfile, which should also print in a matrix/table like [closed]

I just want to get some advice about code optimization. How can I make this more OOP? How many class should I have for this kind of task? My code already works but I was told to use OOP in a way that ...
4
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0answers
55 views

C++14 AtomicRoundRobinPool for sharing a pool of keys

The idea here is that we have some resource that is relatively very expensive to generate, but once we have a bunch of them in a pool, we can keep reusing them instead of generating new ones. "HTTP ...
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1answer
88 views

Fast insert, fast removal and fast access object pool C++ container

I just want to gather some feedback about this container, in my view it solves the problem of common data containers which don't have fast access and fast deletion. I want to admit that I have not ...
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2answers
79 views

A polymorphic union in C++

Sometimes I use std::unique_ptr<BaseClass> when all I really want is polymorphism. For fun, I made this container that skips the heap allocation. The ...
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0answers
71 views

Generic Macro Generated Interval Heap in C

When I saw this amazing data structure I couldn't stop myself from trying it! I first sought resources such as this and an article about it here. It basically works as a Max-Heap and a Min-Heap at the ...
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1answer
37 views

Force ConcurrentDictionary in a Singleton Registry to Collect Removed Items/Space

I have the following class which is used in a WebApi AspNetCore application as a singleton instance to store Strategy objects (reference type). The class is ...
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0answers
66 views

Game involving finding words containing letters from a memorized list

I wrote this Java game where the user memorizes a list, gets given letters and needs to find a word that contains those letters. The player has only a few seconds to enter the word. Example: Program ...
3
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1answer
83 views

Generic Macro Generated Hashset in C

The Hashset uses open addressing, linear probing and Robin Hood hashing for handling collisions. It comes with insert and remove ...
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0answers
61 views

Iterating in a list of data and search data in another datatable

I have a list which has 25000 data and I am iterating in all data and in each iteration, I am searching data in another data table. my whole routine is taking a long time to finish. Loading data from ...
2
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1answer
231 views

Generic Macro Generated Linked List in C

Generate a linked list of any type using macros. The linked list contains functions for adding and removing elements to both ends and also at the middle. You can also add elements relatively to a list ...
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2answers
136 views

Efficient way of flat mapping a range of a multidimensional random access collection

I've recently answered a question about reading elements from an array of arrays. A way it could be interpreted is that the OP wanted to read a range that could span over multiple subarrays of the 2D ...
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1answer
71 views

Wrapper for a standard STL-container

In the codebase I support, I found the following code. I am interested in your opinion about its expediency and especially the expediency of redefining the operator(). ...
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1answer
162 views

Binary Search Tree Implementation in C++17

I am a hobbyist computer programmer trying to learn modern C++ (in this case C++17). I thought it might be an interesting challenge to write a Binary Search Tree similar to ...
5
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1answer
112 views

Data structure that is fast to read and modify

I'm working on an apllication that needs to process a lot of objects in realtime. I've separated the logic from the UI so that it isn't as much of a mess. The basic idea is that every tick I'm trying ...
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0answers
69 views

Further dive into filtering using IPredicate

Preface This is a follow up to my previous post from not long time ago about containers and filtering. This post can be found here. Now, I will attempt to expand what I have learnt from the answer ...
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1answer
171 views

Class containers, filtering and coding practices

Context Usually, when I have to deal with a collection of items (especially objects) I tent to create a container class for that collection (wrapper?). What I mean by that is: when I have to handle ...
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3answers
109 views

My implementation of a for_each function that traverses a std::container by some step size integer N

As my answer to Iterating over an odd (even) elements only in a range-based loop, I wrote this function, with the following driver program and output: ...
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0answers
73 views

Simple generic macro-generated containers

In order to learn macros in C I decided to make a generic data structures generator for other projects that I have in C. The main macros are the following: ...
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1answer
68 views

Extension to BindingList<T> that allows for cancelable notifications of changing and deleting

This is an extension of the System.ComponentModel.BindingList<T> class that allows for notifications of item changing and deleting. These notifications ...
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3answers
531 views

Pass IEnumerable<T> as an argument of method and repository pattern

I've seen tutorials of Unit Testing and I've never seen that IEnumerable<T> used as an argument of method. All authors use ...
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1answer
93 views

java.util.Set extension/implementation

Lately, I was working on some experimental java.util.Set extension, IdSet: ...
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1answer
67 views

Breaking a 32-bit value into bytes for an ArrayList

I am very new to Java and its collections and I'm trying to figure out "best" way to populate an ArrayList<Byte> in Java. In particular, I'm trying to take a ...
5
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2answers
865 views

Going from IQueryable<IEnumerable<myObj>> to IEnumerable<myObj>

I have a "GetPersonsPerDepartment()" method returning a IQueryable<IEnumerable<Person>> while I'm trying to get a simple ...
4
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1answer
144 views

Collections management with many derived elements

I've been told few days ago that using is is a code smell and anti-pattern. I used it in an game to filter some elements of a collection (the inventory of the ...
8
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2answers
5k views

Ring Buffer Implementation in C++14

A ring buffer or circular buffer is a fixed sized queue that advances head and tail pointers in a modulo manner rather than moving the data. Ring buffers are often used in embedded computer design. ...
4
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3answers
122 views

Really easy synchronised access to an IEnumerable without boilerplate code

Often when reading data from a sequence (IEnumerable<T>) in multi-threaded code, a consistent snapshot needs to be taken inside a ...
8
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4answers
791 views

Alternating items in a collection

Is there any better way how to mix items in list? In my example: I want to sort list items as male, female, male, ... My solution is probably very time and resource demanding. Can I do it somehow with ...
8
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3answers
822 views

Moving elements satisfying a predicate from one container to another

I've implemented a C++ algorithm that moves elements satisfying a given unary predicate from one container into the other, deleting them from the input container. This is my implementation: ...
3
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1answer
54 views

Time series dataset with temporally enforced object lifetime

The purpose of this class is to have that can maintain data set where the samples contained within the set have an expiry time. Samples are inserted in chronological order. In an attempt to memory ...
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0answers
19 views

How to connect a propery class/object with a collection (its database class)?

I'm struggling with organizing my code regarding 'best practise'. In particular how I link a class with its collection class. I've 2 classes: ...
8
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1answer
636 views

Generic Skip list implementation in C++ Version 3

This is a follow up of Non generic Skip List implementation in C++ Version 2 If you don't know what a Skip list is: https://en.wikipedia.org/wiki/Skip_list I tried to incorporate as much ...
3
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0answers
38 views

Dependency Container

I'm currently creating my own microframework for learning purpose and I want to make it more powerful by providing a way to register classes and instantiate them (once) only when needed. So here is my ...
3
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2answers
520 views

Non generic Skip List implementation in C++ Version 2

Edit: This code was reworked and repostetd under a new question: Generic Skip list implementation in C++ Version 3 This is a follow up of: Non generic Skip List implementation in C++ If you don't ...
4
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1answer
59 views

General use multi-dimensional container using operator[]

This is a followup to a previous question of mine on same subject. Context I want to have a tool that allows to simulate as much as possible a C++ standard container for a multidimensional ...
4
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2answers
213 views

Non generic Skip List implementation in C++

Edit: This code was reworked and repostetd under a new question: Non generic Skip List implementation in C++ Version 2 To sharpen my C++ skills I tried to implement a skip list. I was quite happy ...
2
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2answers
82 views

Summing payments by year using Java Streams

I'm using 1.8.0_162 version of Java and here is my task about stream framework ...
8
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3answers
160 views

Build clusters from connections (virus propagation)

The scenario is the following: There is a list of persons and places where those persons visit. Each person is connected to a single or multiple places. See the picture below, where O[i] represents ...
4
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3answers
107 views

List mapping of large data set from file

I have a list of items 116 thousand and my mapping function is taking quite some time to process. I am using the file helpers library to write the CSV to disk but its the for each that is taking ...
9
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2answers
247 views

Multi-dimensional container using operator[]

This is a late followup to a previous question of mine on same subject. Context: I want to have a tool that allows to use all the C++ goodies (algorithms, for loop on containers, etc.) on a ...
2
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2answers
464 views

Wrapper for a raw array so that it can be passed to templates expecting Standard Library containers

I am working with a code base where unfortunately I cannot replace all raw arrays with std::array. The spec provides no guarantee that the memory layout of a ...
7
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1answer
114 views

Custom container for iterating over combinations of elements from multiple sets

Motivated by some SO quesitons [1, 2] I made an attempt at implementing a custom container with a bi-directional custom iterator for iterating over all combinations of elements from multiple sets. I ...
5
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2answers
64 views

Filter queries three orders of magnitude slower than insertions

As part of a C++ library, I'm implementing a filter class for approximate set membership and abundance queries. The filter has two primary operations: ...