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22
votes2
answers5714
viewsHow does it work and use the Stack in C#?
I came to a part of my program where I have to apply a stack (stack) and wanted someone to give me a simple explanation and an example. The program that I’m running right now is a notepad where you…
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22
votes5
answers12797
viewsHow to consolidate (aggregate or group) the values in a database?
Suppose I have the following database vendas<-c(100,140,200,300,20,1000,200,3000) vendedor<-c("A","B","A","B","C","C","D","A")…
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22
votes5
answers2395
viewsStrategy to find out if your web application is being partially or fully censored by an ISP
Question Like, conceptually speaking,it is possible to detect that a web application has been partially or totally blocked by an internet provider? Two situations that I believe could allow this…
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22
votes4
answers2442
viewsIn PHP how to calculate a random number?
How to calculate a random integer between 1 and 2000 using PHP, to make a draw? function random() { // codigo }
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22
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answer28962
viewsHow to use debug in Eclipse?
I’m having a very annoying problem with a java.lang.Nullpointerexception error and I wonder if with debug it shows which element is null, rather than just which line is the error.
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22
votes2
answers609
viewsCould current Javascript engines optimize "tail" recursive calls?
In functional programming, it is very common to use functions recursive. Certain languages, such as Scheme, do not even have control structures for loops, depending on recursion to iterate over…
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22
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answers454
viewsSelf-referential global object: what is it for and why does it exist?
The object window in browsers has a property window that is self-reference: window.window === window; // true And there are other similar properties in browsers: self === window; // true top ===…
javascriptasked 11 years ago bfavaretto 64,705 -
22
votes4
answers13539
viewsHow to prevent a click on a link/anchor or tied event element
In the case of a link: <a href="http://www.google.com">Google</a> or in the case of another element having an event tied with addEventListener, what alternatives exist to prevent the…
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22
votes1
answer16031
viewsDesktop notifications in Chrome with Javascript
I have an application where I need to send notifications to the user, and I would like them to appear on the desktop, as the example below. It is possible to do so with JavaScript? If yes, how? Did…
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22
votes3
answers12113
viewsCheck if a table exists in the database
How to check if a table exists in the database before trying to use it? <?php // define a tabela $table = 'banana'; // verificar se tabela "banana" existe aqui // $tableExists = ?? // executa…
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22
votes6
answers34688
viewsHow to send emails only with HTML5 basics
I am building a website to be hosted on a server that does not support PHP or other server-side language. I need to send the values of a contact form by email and my resources are only HTML5 and…
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21
votes4
answers694
viewsWhy not comment on the code?
After reading a bit of Robert C. Martin’s Clean Code, he says that it is no use to "make up" a bad code with comments, in other words, try to explain a gambit made there. It is also quoted about…
terminology characteristic-language encoding-style commentsasked 5 years, 6 months ago CypherPotato 9,292 -
21
votes1
answer929
viewsWhat is the difference between code page, Plane, code point, octet and other terms about characters?
Considering the use of characters that we use to produce texts or other forms of visual representation we have some terms that we need to learn to use the various forms correctly. Has several…
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21
votes2
answers5427
viewsWhat is an automaton?
For several times I hear discussions about automata, whether in the chat or in questions/answers. However I particularly do not know what an automaton is, I have no idea to tell the truth. When…
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21
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answers3969
viewsWhat is Garbage Collector and how does it work?
What is Garbage Collector, how it works? When should we care about him?
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21
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answers4426
viewsIn practice, what is the use of C-pointers?
Recently I have been studying the language and so far I have not identified practical utility for the use of pointers. I understand how it works very well, but nothing more.
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21
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answer2331
viewsWhat is it and what is PCA, LDA, ICA for?
I’m conducting a survey on Facial Detection and Recognition for future implementation, my research has reached the algorithm of Viola Jones and reading more I came to the concepts of: PCA -…
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21
votes3
answers2676
viewsWhen to use SET and SELECT?
I know that as in virtually all issues related to "either" there must be situations where it is best to use SET or SELECT, in a Procedure (for example). At work we always wear the same SELECT, even…
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21
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answers4166
viewsWhat is the difference between array and matrix?
After seeing arrays and programming matrices, I got a little confused, so I was wondering, what’s the difference between a array and a matrix?
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21
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answers17718
viewsWhat to use in Ajax, Success or done?
Sometimes I see them using success, sometimes I see .done, to process the response obtained in the request. Which one should I use? Is there any difference between the two? Which? The same thing for…
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21
votes1
answer21108
viewsWhat is the purpose of the RESTRICT, CASCADE, SET NULL and NO ACTION options?
When creating a foreign key type relationship between two tables in Mysql, I can specify some additional options in the events ON UPDATE and ON DELETE that are associated with alteration and…
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21
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answer3524
viewsWhat does the asterisk in "* {}" mean in CSS?
Sometimes I take sites ready to edit and realize that the console appears: * { /* código aqui */ } What does that asterisk mean?
cssasked 7 years, 8 months ago Lucas de Carvalho 6,427 -
21
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answer631
viewsWhat is the difference between DI, Factories and locators?
Already I asked about addiction injection. It is widely used. In my opinion it is even abused. But I saw that in her place you can use Factories or locators. What would they be, what are the…
pattern-design software-engineering dependency-injectionasked 7 years, 10 months ago Maniero 444,682 -
21
votes1
answer7017
viewsWhat is the POSIX?
I know the acronym Portable Operating System Interface (POSIX), but what is it? Does it have to do with UNIX? Windows cannot be POSIX? What this matters to the developer?
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21
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answer1449
viewsWhat are the SOLID principles?
Lately, I’ve heard a lot about the term but for me it’s never clear if it’s a Pattern design or good practice in object orientation. Maybe it’s a very broad question, but why SOLID is useful and…
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answers4047
viewsWhat are the main differences between JSON and BSON formats?
I’ve been reading an article on Internet, where they commented on the format BSON(Json Binário), but I was left with some doubts about: What is the BSON? For what reasons he was created? There is a…
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21
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answer1658
viewsHow to document SQL code?
When I write R codes, the correct way to document is in the code itself, in the form of comments initiated with a special marking #'. #' Add together two numbers. #' #' @param x A number. #' @param…
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21
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answers249
viewsWhat is a Saas anyway?
I was reading this question What is cloud computing? and I was left wondering which line separates normal software from a Software as a Service (Saas). After all, what is a Saas? And what are the…
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21
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answers868
viewsWhat is the purpose of alt in a <img /> tag?
Studying on HTML5 I came across the property alt being used in tag <img />. Example: <img…
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21
votes2
answers4131
viewsHow can Whatsapp insert Emojis into the URL?
If you search for "Whatsapp" in Google, the result is this: Apparently this "" in the url is a feature that makes the internationalization of the web application. After accessing this page, the…
urlasked 8 years, 7 months ago Renan Gomes 19,011 -
21
votes3
answers866
viewsWhat are "Magic Numbers"?
My IDE informed that I am using magic numbers in my code, in the stretch f = 12. I’d like to know more about "magic numbers". I need to have a variable with a value of 12, but the IDE said something…
encoding-styleasked 8 years, 7 months ago durtto 3,109 -
21
votes3
answers2168
viewsHow to Make Icone Ride in the Google Maps api
In this My script below it every 30 seconds causes the icone to change position, only the icone disappears and appears at the next point. What I wanted was for him to walk up to the next point as…
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21
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answers548
viewsWhat’s the difference between a js file with . min and no . min?
What is the file difference Javascript containing .min (for example jQuery.min.js) and the file without the .min (for example jQuery.js)?…
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21
votes6
answers1578
viewsIs it good practice to use constructors (or magic methods) in interfaces?
Well, I usually come using interfaces to define how some methods will be used. But to be honest, I’ve never seen anyone using interfaces to define contracts for a construtor. In a specific case I…
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21
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answer1446
viewsOrganizing packages in a java project
When creating a project on Android, the IDE itself suggests that the main package has its own naming type (with.example.namepackaging), and also creates a whole hierarchy of directories already…
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21
votes3
answers10118
viewsWhere should the business rule be in the MVC standard?
A few weeks ago I started to study in depth ASP.NET MVC and, as I came from Windows Forms, there are some things that have not been very clear yet. In all the applications I’ve done so far in this…
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21
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answer622
viewsAt what times is it necessary to force garbage collection in C# for better application performance?
Usually I always have doubts about the use of functions for memory release, in which situations should it be used or should it always be used? And mine really will perform better? If possible…
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21
votes2
answers6309
viewsHow to remove a CSS attribute with jQuery?
In jQuery, it is possible to add an attribute to an element through the function attr. You can also remove an attribute through the function removeAttr. And when I define an attribute of css through…
jqueryasked 9 years ago Wallace Maxters 102,340 -
21
votes2
answers8871
viewsHow and when to use Interface?
When should I use an interface, in which situations its use is feasible and which is not feasible and how to use it correctly? I developed an example to illustrate a situation, below: using System;…
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21
votes1
answer1790
viewsWhy is Language D rarely used?
I’ve done a lot of research on the language, I’ve used compilers, Ides (Eclipse, Mono, Codeblocks). I thought she was "too good to be true". It has the whole structure of the Java/C# syntax (which…
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21
votes1
answer329
viewsHow to implement memoization in a PHP function?
I saw it today in a reply the following code: function fibonacci($n) { $a = 0; $b = 1; $c = 1; for ($i = 1; $i < $n ; $i++) { $c = $a + $b; $a = $b; $b = $c; } return $c; } echo fibonacci(100)…
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21
votes6
answers502
viewsEmpty semicolon doesn’t make a mistake?
I was working on a project and unintentionally bumped into the semicolon that ended up being inserted well after a if. I was intrigued because Visual Studio did not point out as an error, and when…
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21
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answers210
viewsMarking IP Tos Field in Openflow
I’m a beginner in all this, so I have a question. Considering a video call app DASH IF (Dash.js) which is executed (emulated) in a mesh network characteristically SDN (Software Defined Network). I…
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21
votes6
answers8730
viewsHow to create geometric shapes using CSS?
How can I make the geometric shapes below using preferably CSS? If not possible using CSS only I also accept answers with other methods.…
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21
votes5
answers1899
viewsIs dealing with business rules in the model bad practice?
This is something that may seem simple, but it is not. After all how to define whether a rule should be in the service layer or in the model itself? To illustrate, think of the following: We have an…
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21
votes1
answer487
viewsHow do I make Google understand my Links?
If we type Globe in Google the result appears as the image above. 1 - How can I make my site look like this too ? 2 - Google does this on its own ? I am in the tool of Google Webmaster Tools and…
seoasked 9 years, 3 months ago Diego Souza 16,524 -
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votes2
answers48433
viewsUsing WITH AS command in Sql Server
I have seen this example below, I would like to know how this command With [name] AS works on Sql Server, and what are its uses compared to tables in memory or SubQueries, in terms of performance.…
sql-serverasked 9 years, 4 months ago Roger Oliveira 682 -
21
votes6
answers65532
viewsSum in 2 inputs and appear in real time - Javascript
My question is the following: I have two inputs type text. One person put a number in input 1 and another number in input 2. When the person had just filled in, the result of adding the 2 inputs…
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21
votes1
answer6034
viewsWhat is the storage limit for Sqlite?
A new demand for the application of the company where I work, I need to store more than 100k of records in different tables, I’m worried if the Sqlite will withstand such demand, my question is:…
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21
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answers11055
viewsWhat is the advantage of using the ENUM type?
When I should use the guy ENUM because even today where I saw this guy being used he could be replaced by VARCHAR or even for a simple CHAR, I can’t see a case where in it it really becomes…