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101
votes
8answers
16k views

Why is polling accepted in web programming?

I am currently working on a Ruby on Rails project which shows a list of images. A must-have for this project is that it shows new posts in realtime without the need of refreshing the web page. After ...
14
votes
8answers
31k views

Techniques to increase logic at programming [closed]

I am into programming since last 3 years. But I seems to be lost in it. I am not able to get good at it even though I code everyday. suppose I solve one problem, I will wander from solution to ...
11
votes
3answers
4k views

How to unit test method that returns a collection while avoiding logic in the test

I am test-driving a method that is to generate a collection of data objects. I want to verify that the properties of the objects are being set correctly. Some of the properties will be set to the same ...
8
votes
2answers
269 views

Is it common practice to transform requirement specifications into predicate logic for functional programming?

I've recently been assigned to work on a small project which is being implemented in Haskell. Coming from an OO/imperative background, I'm used to converting requirements/user-stories into use-cases ...
7
votes
5answers
3k views

Why is there both a short-circuit OR as well as unshort-circuited variation of that operator in C#?

Periodically, I wonder about this: The short-circuit OR would always return the same value that the unshort-circuited OR operator would? I expect that the short-circuit OR would always evaluate ...
7
votes
5answers
349 views

In retrospect, has it been a good idea to use three-valued logic for SQL NULL comparisons?

In SQL, NULL means "unknown value". Thus, every comparison with NULL yields NULL (unknown) rather than TRUE or FALSE. From a conceptional point of view, this three-valued logic makes sense. From a ...
5
votes
4answers
368 views

In which order should I do comparisons? [duplicate]

I'm a strong proponent of writing if statements like this: variable == constant Because to me it just makes sense, it is more readable than the inverted: constant == variable Which seems to be ...
4
votes
2answers
1k views

Logic design question for SQL query

Was wondering if you could help me on a SQL problem I’m having. I have a set of records of events where each event has a start time and end time. No event has the same start time, and the end time ...
3
votes
1answer
103 views

Tests for emptiness vs tests for nothingness

Is there any consensus between languages how tests for emptiness are distinct from tests for noneness? In python the following expression is false: {} is {} However this expression evaluates to True ...
3
votes
3answers
406 views

Matching up articles with similar ones

I am creating a site where people can write on a niche topic. It is almost like a blog, however the area as I mentioned is a small niche with (hopefully) passionate users. I want a functionality ...
2
votes
2answers
80 views

From a set of rules, derive the implications? [closed]

I've only just become interested in this domain, so sorry if I'm not using the correct terminologies. What I want is the following: Say I have a set of rules (or constraints), I want to derive some ...
2
votes
1answer
6k views

Mobile number validation

I am trying to find best way to validate a mobile number with in a country. Currently my understanding is: User can enter whatever format they want in mobile numbers and its a waste of time and ...
1
vote
3answers
418 views

Is “code that generates code” really all that great?

I was looking through CodePen's "popular pens" and I noticed this cool little spiral animation somebody made with a seemingly ridiculously small amount of code. This is quite impressive until you ...
1
vote
1answer
183 views

What algorithm can be used to determine order given incomplete information?

Given a series of statements such as: a<c a<b b<c (Read as "a is before b", "a is before c", etc.) What is the order of the elements? In this example, the answer is a<b<c. A less ...
1
vote
1answer
417 views

Finding possible positions for rectangle in a 2-d array

Well, the title is not very appropriate, please read on (I couldn't get a better one). Note: Using Python 2.7, but an algorithm will help too. I'm making a side scroller game, in which I am ...
1
vote
2answers
414 views

How Do Computers Process Conditional/Input/ Event Based Code? [duplicate]

I understand that computers are basically a complex system of electrical signatures that can calculate based on logic boards, and some sort of gate mechanism, but how do computers process something ...
1
vote
1answer
257 views

Data model for persisting queries to database

I have been asked to build what is essentially a query builder for a reporting application. The variety of objects to query, potential modifiers, number of conditions, and so forth to be reported on ...
1
vote
2answers
578 views

C# Logic - gaps & Islands

I am looking for help designing the display of available times for appointments (for example a hairdresser's appointment book). Currently I have a query that returns a collection of periods that are ...
1
vote
0answers
39 views

Logic to find the number of requests which can be open at any point of time

I am trying to build an application which tries to find out if a system is suffering from backlog (# of requests which are open are more than what the team can handle) I have the below parameters ...
0
votes
1answer
221 views

Understanding bitmap logic

I was going though this blog and it says You can represent a list of distinct integers no larger than N using exactly N bits: if the integer i appears in your list, you set the i th bit to true. ...
0
votes
1answer
60 views

Possibility of retrieving X value after Bitwise OR operator

Z = X ∨ Y (where X, Y, Z are 96bits binary numbers) If I have "Z" value and "Y" value. Are there any possibilities to retrieve "X" value from "Z"? What I know is it is possible to do this with XOR ...
0
votes
1answer
170 views

Calculating WPM given a variable stream of input

I'm creating an application that sits in the background and records all key presses (currently this is done and working; an event is fired every keydown/keyup). I want to offer a feature for the user ...
0
votes
1answer
108 views

Logic behind an 'undo' for painting on a canvas

I'm working on a module that allows users a basic paint function. I want to support undoing any modifications done to the painting surface. Assuming that we have one layer (for the sake of ...
0
votes
2answers
252 views

in trouble making a card game with pygame

I am designing a card game playable against the computer. The rule is very simple Both player and CPU gets 10 cards of 1 to 10. Player and CPU plays a single card at the same time, every round. The ...
0
votes
0answers
26 views

Qualification problem in situation calculus

I am learning AI situation calculus by defining a situation via a situation calculus through the use of states, actions and affects for a robot vacuum world. The question is to what extent do i need ...
0
votes
0answers
191 views

Finding meeting point of Slow and Fast pointers in Linked List Loop

I am aware that the solution for finding a loop using Hare-Tortoise approach works. I have a working code that is able to detect loops in a Linked List. My question is on how to find the meeting point ...
0
votes
1answer
275 views

Creating algorithms [closed]

I am a relatively new programmer. I can pick up languages and learn syntax at a speed that I consider good, but I can't figure out how to solve problems logically using algorithms very well. I know ...
-1
votes
4answers
146 views

Identifier for the “completed” stage of a process: 0, 99, something else? [closed]

Say, that you are handling a multi-step process (like a complex registration form, with a number of steps the user has go through in order). You need to be able to save the current state of the ...
-1
votes
2answers
532 views

How to remove data redundancy in a table? [closed]

F1 F2 F3 C1 C2 C3 ------------------------------------------------ A B C 1 D E F 2 A B C 3 D E F 4 A B C 5 D E F 6 ...
-3
votes
0answers
43 views

Size Procedure in Prolog Language [migrated]

I am new to prolog and am not that great when it comes to recursive algorithms as is, thus I am confused with the following two clauses: size([],0). size([H|T],N):-size(T,N1),N is N1+1. I am having ...
-4
votes
2answers
224 views

How can I Identify which condition satisfied the if statement? [closed]

Suppose, I am using a if statement as such: if(A || B || C || D) { echo "Hurrah! if is satisfied!"; echo "But! How can I know which was true of the 4 (A,B,C,D)"; } Is there any way I can ...