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Questions tagged [array]

An array is a systematic arrangement of similar objects, usually in rows and columns.

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is it better to have tracking fields that are maintained separately for arrays? [duplicate]

I wasn't sure exactly how to word this question, but basically, I have a struct stNeuralLayers (for a neural network I'm playing around with) with fields that are matrices (such as a double[,] ...
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2answers
149 views

Should execution continue if array is empty?

Just a general programming best practices question. If I have a function like that takes in an array of items and the function then calls a series of other functions which filter and act on the items ...
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1answer
78 views

How should I define hardcoded strings with some variable parts? Reuse more characters? Or keep the whole sentence?

for example, sometimes I need to define a hardcoded string with some variable parts, I often have trouble to choose the style: style 1 : reuse every characters when possible showMessage(num){ let ...
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2answers
343 views

Should I use Array or Set if both can be used to finish my task?

for example, Suppose I have a 2d array: let filterArr=[ [1,1,0,1,1], [0,1,1,1,0], [1,1,0,1,0] ]; I want to find and store the index of column that all are 1, i.e.:position 1 and 3, and the ...
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1answer
146 views

For arrays, should I use the first position to store the selected element, instead of variable like “selectedIndex”, if possible?

For example, I have a toggle button, which would show the current selected element, and would show next element when it is clicked, and it can loop back to first element. I have 2 ways to store the ...
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1answer
94 views

Should special case be inside or outside the for loop here?

For example, suppose I have 2 arrays: let arr1=[5,2,1]; let arr2=["abcde","ab","a"]; my work is simple : to check if length of strings in arr2 are larger than corresponding element with same index ...
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2answers
119 views

Should I move tasks which is just for a specific element only out of for loop?

For example, I have a for loop, which element 0 has additional function to run compared with other elements, my question is, should the additional function be: 1.place inside for loop for(int i=0;i&...
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3answers
169 views

How do I put objects of different types derived from a common base in the same array? [closed]

I have two classes called Player and Enemy both inheriting from a class called GameObject, how do I store them both in an array of type GameObject while still keeping their own unique information? I ...
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1answer
104 views

Array rotation algorithm

I'm developing an application which sends quotes to clients via email. Since quotes are obtained from various resources (per each client) they end up in a single array which is then used as a source ...
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2answers
536 views

How does a dynamic array access work?

In C if i declare int x[4] Which tells me its an integer array with each array element size fixed of size 4. So after initialization when I access x[3] : address of array +element size which is 2 *...
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2answers
86 views

Linked-list iteration patterns

If you have a linked-list, where the items are not necessarily close to each other in memory, wondering if it is (in general) better/worse/no difference to do the following. Say you want to iterate ...
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1answer
111 views

What is best practice for handling mapping arbitrary depth in arrays?

I have a set of data: id | name | parentid ------------------------ 1 | parent | 0 2 | child | 1 3 | child | 1 4 | parent | 0 5 | child | 4 6 | subchild | 5 7 | child | 4 ...
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2answers
1k views

How exactly indexing works in arrays?

I only know that index is faster but don't know why is it faster. Suppose I have an array int[] a = {2,3,6,7}. Then I will try to find the element at a[3] and the speed of this will be O(1). Why? How ...
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2answers
796 views

How did the custom of using square brackets for array elements develop?

Many programming language use the syntax a[i] to refer to the i'th element of an array, sequence, or vector a - specifically, C and Pascal (from the late 1960s and early 1970s) do this. On the other ...
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2answers
165 views

Are there any use cases for List when Deques and Arrays are available?

I've been thinking about this over the past few weeks, and I've come up with no good arguments. My perspective is from Java, but if anyone has any language-specific cases outside of this language, I'...
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4answers
98 views

Store csv data as rows or columns in view of the needed processing?

Assume I have some data a csv-Files like ObjectName, PropertyA, PropertyB, PropertyC "Name1", 3, 1, 4 "Name2", 1, 5, 9 "Name3", 2, 6, 5 ... and a typical question I want to answer would be For ...
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3answers
452 views

Is “Array[1]” the first element or second element in the array?

Following the reading of the question Why are zero-based arrays the norm?, I wonder about the terms to use for referring to specific array elements, in the perspective of linguistic reading of ...
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1answer
92 views

What is the name or description of my technique for filtering items in array? [closed]

I've tried posting this question on StackOverflow but they told me to try it here since it's not so specific. I'd like to know the name of the algorithm or technique of following implementation. I ...
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0answers
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speed up search in string array [closed]

Suppose we have sorted array of strings e.g. std::vector<std::string> or some other elements with string as key - for example std::vector<std::pair<std::string,data_type>. Normally to ...
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0answers
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How should I store a frequently accessed array with an unknown number of elements in mongodb?

I have a simple "Index" object defined as follows: { "position": 4, "value": 345 } And I'm trying to figure out the best way to store this object in a mongo database, assuming that: The "...
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1answer
485 views

Why is it possible to access an array out of bounds with negative indexes much further than with positive indexes?

I have written two small programs in which I declare a very small array. Then I try to access values out of bounds. The interesting thing I noticed that when I try to decrement the index I can ...
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2answers
160 views

Is it unnecessary to have a method that merely loops through an array and calls another method with each item?

For example, if there's multiple lines to be drawn, I could do function drawLines(lines) { lines.forEach(function (line) { drawLine(line); }); } function drawLine(line) { //... } ...
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3answers
1k views

Return array pointers vs. populating an array inserted as a parameter?

Which is better? I noticed the latter is used in a lot of C code. People will typically malloc an array, and then pass that as a parameter to a function, which will then populate it. Whereas in Java, ...
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Best practice on naming an array (i.e. an array of image file names) [duplicate]

I have an array of image file names. e.g: [ 'a/b/foo.jpg' 'c/d/bar.jpg', 'example.png' ] However, I am confused as to what the best practice of naming this array. Would it be: ...
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1answer
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How to create a method that takes array list as argument?

To create a method that takes an array as an argument, you would do this: public static void printAges(int[] age) { // prints ages to screen for (int x = 0; x < age.length; x++) { ...
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1answer
147 views

Handling out of bounds requests in embedded C library

We're currently building a library in C that configures itself from tables in EEPROM. This leaves the possibility however that some caller requests a field that is out of bounds, and the question ...
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1answer
589 views

Merging algorithm for overlapping intervals

I have been searching for an efficient algorithm to merge overlapping intervals on a dynamic array of intervals. For example, (start time, end time) wise, [(1, 2), (4, 8), (3, 10)] becomes [(1, 2)...
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1answer
582 views

Lower bound for finding a value in sorted array

Suppose we have a sorted array of unique elements, A[n]. I am trying to find the lower bound for finding a specific element x in the array. I suspect the lower bound to be log_2(n+1). I tried to use ...
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5answers
690 views

Fastest algorithm of dividing array into positive and negative numbers

Given array of integers I am trying to design the fastest algorithm that swaps the elements such that at the end : all negative elements are on the left and then the positive elements, for example, ...
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2answers
5k views

Check for empty PHP array

An empty array in PHP is considered falsey. That means the following will not print anything as the array is empty. <?php $myArray = array() if ( $myArray ) { print "My Array is NOT empty"; } ...
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1answer
534 views

Should objects be singular since arrays are plural?

Might be a silly question, but what is more logical: object.actions.bark() or object.action.bark()? Simply about plurality. I know arrays are usually pluralized. But if I were to be consistent; ...
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2answers
242 views

How do I best store a value with multiple keys?

I need to store two 32-bit numbers in a way that is quickly accessible and as storage space efficient as possible. My keys are a combination of the following two values: port: 0 - 29 vlan: 1 - 4095 ...
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0answers
444 views

Best way to handle large amount of objects

I'm building an javascript application where I need to register devices to an specific room. So I thought, I'm making my room_name as main key (room name is unique). And I'm going to add the devices ...
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2answers
231 views

Arrays vs Dynamic Arrays

In Steven Skiena's The algorithm design manual Edition 2, he talks about dynamic arrays on page 67, which results in them having same Big-Oh as normal arrays. I don't understand how. This is what book ...
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4answers
1k views

How does C know the bounds of a multi-dimensional array?

Coming from Python, if C does not have array bounds, how does it know where a[1] starts? int a[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; b = a[1][1];
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3answers
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Professional way to produce a large problem without filling up huge arrays: C++, free memory from part of an array

I'm developing a physics simulation, and as I'm rather new to programming, I keep running into problems when producing large programs (memory issues mainly). I know about dynamic memory allocation and ...
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4answers
2k views

size_t or int for dimensions, index, etc

In C++, size_t (or, more correctly T::size_type which is "usually" size_t; i.e., a unsigned type) is used as the return value for size(), the argument to operator[], etc. (see std::vector, et. al.) ...
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3answers
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Building a simple AI for Noughts & Crosses game

I'm developing a simple noughts & crosses game where the player plays against the computer. Obviously, I use the Randomize function of the language, however, the final stage of refinement is to ...
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4answers
1k views

how to speed the random access of 2D array? [closed]

arr[2^30][100000] for (int i = 0; i < 2^28; i++) { value = a*b+c;//only a example. In all, value is an integer. arr[value][arr[value].length++] = i; } My code like above. Random access a ...
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1answer
674 views

find longest subsequence with sum less than or equal to k

I have a vector<int> num, I want to get the size of longest subarray with the sum less than or equal to k. My approach: O(n^2). Repeat for every element in the array. Can we do better?' ...
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1answer
30 views

Creating block of data from a large input data

I am working on an algorithm whose specs says that it accepts 32 bit input (long type). My actual data is 14 bytes e.g 11:12:12:04:DD I have created sub arrays like subarray1[4]={'1','1',':',1} // ...
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3answers
400 views

Find if any pair exists in an unsorted array?

I have come across a programming question in which I have to determine : Does there exists at least one pair in a given unsorted array such that |i - j| <= K and |A[i] - A[j]| <= x ? ...
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1answer
66 views

How to fit k-length arrays to number of bigger arrays?

I have n number of one-dimensional arrays similar to: [0,0,0,0,0,1,1,1,0,0,1,1,...] 0's and 1's indicating occupation. And k number of smaller arrays similar to: [2,2,2], [2,2], [2], [2,2,2,2] ...
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1answer
523 views

How to ask a user how many inputs they want

I want to know if it possible to use arrays for a more viable alternative of getting a non-predetermined number of inputs as an array and with an indefinite number of inputs. (python) original code --...
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2answers
2k views

Example of problem caused by casting Object[] to E[]

I've heard here and there that arrays contain runtime data about their type, making you unable to instantiate an E[] (E being a generic type parameter, for example in a class Foo<E>), and that ...
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1answer
216 views

Is there anyway I can store the static std::vectors of pointers of all my derived classes in my base class?

I currently have a program that has multiple derived classes. All instances of a derived class are stored inside of that class's static vector of pointers. I also have a static vector of pointers ...
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2answers
2k views

Is it good practice to use array.pop() assignment in a while loop condition?

Just saw a code snippet that used an array pop assignment in the while condition; was wondering if this is acceptable/good practice? var arr = [0,1,2,3,4,5]; var current; while (current = arr.pop()) {...
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2answers
519 views

Having trouble with AP computer science sample test problem

I am currently taking AP Computer Science at my high school and while looking at some sample AP test problems I came across one that really confused me. Sample Problem The answer to the problem is ...
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4answers
252 views

Chunking an array into letter groups that are generally equal length

Given a list of items, I want to break it up into four groups with as equal length as possible. The items need to stay grouped by the first letter in each item as well. 26 letters / 4 groups would ...
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1answer
275 views

Algorithm to find the highest Tetromino in a Tetris board?

Lets say that our Tetris board is represented as a 2D array of zeros and ones, where a 0 means empty and 1 means occupied, and you where asked to find the highest row in which a tetromino exists. ...