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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3
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2answers
54 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 ...
4
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0answers
62 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
32 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 ...
2
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0answers
58 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
76 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 ...
2
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1answer
113 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
129 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 ...
1
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1answer
70 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(). ...
8
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0answers
118 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 ...
1
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0answers
74 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
65 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 ...
8
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1answer
155 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 ...
4
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3answers
86 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: ...
2
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0answers
50 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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0answers
22 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 ...
4
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3answers
511 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
92 views

java.util.Set extension/implementation

Lately, I was working on some experimental java.util.Set extension, IdSet: ...
0
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1answer
57 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
863 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
138 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 ...
6
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2answers
2k 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
111 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
771 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 ...
6
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2answers
659 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
52 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 ...
2
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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
493 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 ...
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0answers
37 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
388 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
58 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
181 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
79 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
158 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
227 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
352 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
103 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: ...
4
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1answer
240 views

Fast insert unique container

I posted the same question at StackOverflow then I got an advice to post it here. Original question: https://stackoverflow.com/questions/49998297/fast-insert-unique-container I have to store ...
3
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3answers
85 views

Fill in workbook with data from another workbook

Followup to this question I made a macro that will fill in data in a workbook that has 65 (24 are user filled) columns and can go as long as 1500 rows. The macro can import about 1500 rows and 24 ...
3
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1answer
142 views

Finding the lowest possible number of changes to turn one string into another

I've been working on a task: I have two giant strings, both consist of the same characters just scrambled (both consist only capital english letters). The task is to find the lowest possible number of ...
4
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1answer
72 views

Fill a new Workbook with info from another workbook

I made a macro that will fill in data in a workbook that has 65 (24 are user filled) columns and can go as long as 1500 rows. In an ideal scenario, the workbook has a perfect column that could work ...
4
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0answers
117 views

C++11 Removable connection from emitter or receiver object

Please review my solution for the following problem. I am interested in: Maintainability Usability Logical correctness Efficiency Problem: It has 1+ objects each in separated thread and between the ...
5
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1answer
500 views

Complete ObservableDictionary

In conjunction with a recent question of mine, I found that an ObservableDictionary would be very handy for my situation, so I decided to implement one. I've ...
1
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1answer
739 views

Set, List and Map equality comparison with Lambda check

I'd like to be able to compare two objects with different equality checks. This should work if they're in a Set, List or ...
3
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2answers
2k views

Example of adding STL iterator support to custom collection class

I'm trying to create an example of a custom collection with an API meeting the requirements of STL iterator templates, as a learning experience. The collection used here, a ring buffer, is merely a ...
5
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1answer
108 views

C++ container — variable byte coded numbers list

I'm writing a container for unsigned integers, which uses variable byte coding. It works but some decisions I took look ugly so I would be glad if you gave me some hints for improving the design. I ...
0
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1answer
44 views

Create numerical-key array from existing string-key array, with a given string-key as first item

I have an array of available languages for my website, with a short ISO country code as the key for each language. I need to create a new array that contains the same info, but with numerical keys and ...
6
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2answers
639 views

Iterator of Container of Container

Based on this question I though I would pull together an iterator that iterated over a container of containers. ...
1
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1answer
537 views

Returning containers from function - C++ [closed]

I've been trying to implement a few interfaces for processing data. And most of the time I do new of container and return a smart pointer to this container. ...