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13
votes2
answers1533
viewsMaterial for the study of functional languages: scala, Haskell and Erlang
Well, I asked a question recently and it was suspended because it is a matter of opinion of each person, so here I repeat my question to be more clear what I want: Could someone please pass me…
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13
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answers1215
viewsWhy create an interface for each DAO?
I see a lot on the Internet the creation of an interface for each system DAO. I understand the importance of using interface mainly for an easy implementation exchange, I have even found an…
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13
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answer1771
viewsHow to perform automatic pull with Git?
Imagine that I have a test environment for a web application, where there is a cloned Github repository that is directly inside the server, and any modification in it already results in a real-time…
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13
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answers16707
viewsHow do the SHA family hash algorithms work?
I would like to understand how the hash algorithms of the SHA family work (Secure Hash Algorithm), such as the SHA-1, SHA-2, SHA-3, and understand the differences between them. I seek didactic…
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answer369
viewsWhat tags can I use to document my code?
I’m looking for better ways to document my code in Netbeans. Besides the tags known and used in Javadoc something caught my attention and aroused my curiosity. When typing {@ some suggestions of…
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13
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answer5489
viewsHow to create directory with a path that works for any OS?
I am doing a job in Java and I need my program to create a directory in the user’s "home" folder, but it needs to be able to create both in Linux and Windows. It is possible to create a "generic"…
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answers1574
viewsDatabase and transaction control in value transactions
In my project I need to develop a system of transactions where the user will put credit and the services he hired will consume these credits. I built the following structure but I don’t know if it’s…
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answers668
viewsWhy is a Fibonacci faster in Java than in C?
Not exactly like this, but I noticed that when the function needs more time to compute Fibonacci, Java actually does better than C. Here are the implementations: C: #include<stdio.h> unsigned…
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answers2486
viewsHow to make this arrow in CSS
I have this next arrow in a layout, but I don’t want to make an image, but only with CSS. How do I do? I have to wear edges?…
cssasked 10 years, 2 months ago Felipe Viero Goulart 3,693 -
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votes4
answers7358
viewsHow to jump to the next field using jQuery?
How to move focus to the next field of a table using jQuery? I have a table with the fields Id, Name and Price, the price column is a text input. How to implement a feature for when the user presses…
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13
votes2
answers1285
viewsCkeditor html content is empty after using jQuery-ui Sortable in your parent div
I want to leave "sortable" 2 or more div’s with a Ckeditor populated with html, but when doing this the html of Ckeditor loses the content and the editing space is blocked. Fiddle next:…
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answer27404
viewsDifference between CAST and CONVERT in Mysql
To solve a problem I came across two solutions where a function was used CAST() to convert a number into text, the function was used in another CONVERT() for the same purpose. The two functions, the…
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answer767
viewsWhy does PHP allow you to create identifier names with special characters?
Typically in programming languages and databases, identifier names (variables, functions, classes, methods, tables, fields, etc.) must start with a letter or underline, numbers can come in sequence…
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answer796
viewsHow to treat exception in a Webview?
I wanted to know how to treat exceptions in my Webview, because sometimes the site ta off, and the page does not load, and sometimes even crashes the application. I tried a try catch no load, but…
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answer462
viewsOperator NOT (!)
Guys, I’m kind of not knowing how exactly the operator works (!). I always get confused when it comes to using it because I don’t really know how to apply it. It only works with parameters equal to…
javascriptasked 10 years, 3 months ago ropbla9 6,810 -
13
votes5
answers53548
viewsMysql decimal value
I am trying to insert decimal value in mysql database, wanted to put these values for example: 1.500,00 Thousand, hundred and ten What is the type of column I must declare?…
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votes5
answers16703
viewsFill left zeros in Javascript
I need to insert zeros left into a field input text. Whereas this field might even be 5 characters + one check digit That is, I need Javascript to fill in zeros to the left according to what the…
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answers1955
viewsPre-process large text files in R
I am writing a script, which I will make public, to open the micro-data of RAIS (dehydrated, available here) in R using Monetdb. However the bank does not accept vígula (,) as decimal separator.…
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answers2383
viewsMore important than important
My style sheets declare formatting for a class more or less like this: .foo div label { width: 100px !important; } This comes from a plugin. I would not like to change the plugin’s style sheets, but…
cssasked 10 years, 3 months ago Oralista de Sistemas 23,115 -
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answer8955
viewsInheritance in relational database
one of the great challenges in developing object-oriented software is to abstract the data from its base to power-like objects better manipulate them, today the available ORM frameworks make this…
database oop modeling pattern-design inheritanceasked 10 years, 3 months ago Tuyoshi Vinicius 4,046 -
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answers1143
viewsAdd rownames as column using dplyr
I would like to do something that is quite simple using the common R syntax, but using the package dplyr. The task is basically to add the row.names of an object data.frame as column on that same…
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answers317
viewsWhat are the most common problems and dangers when enabling `register_globals` in php?
I recently asked the following question How the file receives the $_POST? Based on the comments and the answer I was interested to know the main problems and dangers of having this function enabled…
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answer1570
viewsHow to find out if Javascript is disabled?
How can I check and show the message to the user that the browser Javascript is disabled? For example, it will do something, and if its Javascript is disabled I show this message to it, so that it…
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answers1065
viewsObject orientation in R: S3, S4 and Reference Class
R has, among others, three main forms of object orientation: S3; S4; and, Reference Classes. What are the main differences between the three methods? And how to implement them (preferably provide a…
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answers4991
viewsBack to Top of page
I need to have a fixed icon on the page in the right corner below the screen. By clicking this icon he goes back to the top of the page, doing the Scroll scroll to the top of the page. Could someone…
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answers759
viewsComparison between a numeric string and an alphanumeric string
The following operation returns true: var_dump("1" == "1e0"); //1 == 1 -> true But if I add an "e" at the end of the second string, it already returns false: var_dump("1" == "1e0e"); //1 == 1…
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answers3561
viewsJava and Offline Databases
I need some help with a Java database. I want to make a database that the program generates a file, such as "database.db" and this file I can access without any internet connection, using only the…
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13
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answers477
viewsJava Performance of methods-filled and empty classes
If I create a class whose goal is to group a number of related methods. Suppose a Class Boi{} and it has several methods but no element. For example: public class Ruminante{ public String…
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answers1081
viewsWhat are the advantages and disadvantages of Duck Typing?
Duck Typing is a principle that states that one should not use inheritance or interface to define which methods a class should have. Example: # ruim class Animal # método abstrato def speak end end…
encoding-styleasked 10 years, 5 months ago user7261 -
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votes6
answers1170
viewsWhy is it not possible to define an interface with static methods?
I would like to force some of my classes to be implemented in Singleton, but I came across the following situation. interface ICharacterSingleton{ static Characters getInstancia(); } public static…
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13
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answer1351
viewsHow to know the scroll direction of the mouse wheel
How to know the direction and quantity of the scroll when scrolling with the mouse wheel? Browsers have different ways of passing information on the object event. Some use the .wheelDelta, others…
javascriptasked 10 years, 6 months ago Sergio 133,294 -
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answers1173
viewsIs it safe to minify HTML?
Like JS and CSS, HTML can also be "minified": <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge">…
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answers3635
viewsWhat is metaprogramming?
Sometimes we hear about "Metaprogramming". What is? What good is? How and when to use?
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answers1652
viewsHow to perform TDD on the Service layer
I participate in a project that uses MVC layers with Hibernate framework persisting in a Postgres. Junit is used for testing and Mockito is used for mocking (I still have no knowledge and practice…
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answers1997
viewsHow to detect Ajax Request?
Is there any way in PHP to detect if the request made is Ajax?
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13
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answer233
viewsHow to calculate the dimensions of an SVG element
How to calculate the dimensions of an element svg consistently across browsers? In fact the only one not to respond consistently is Firefox. It would be interesting to understand the reason for the…
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13
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answers2568
viewsOWIN and Katana - How does it really work and how to use it?
In recent times I have tried to understand better about OWIN in the aspects of why to use it, how it works and how to use it. About why to use I have asked here and already convinced myself that the…
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answers1131
viewsOpen/closed principle - how to understand this?
In object orientation there is SOLID and one of the principles is the open/closed one that I learned as follows: "software components must be open for extension and closed for modification" and…
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answers17303
viewsWhat is the best way to read an XLS file?
I would like to know the best way to read an XLS file in C#. I can handle it the same way I handle a database table?
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answers8540
viewsJavascript floating point account realization with absolute precision
I am working with financial values and when it comes to performing mathematical operations in Javascript, the values are not as expected. console.log(11.8-10.2) 1.6000000000000014 I would like to…
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13
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answer671
viewsVisual Studio 2010 lag
I’m a beginner in programming and got a very good study material for Visual Studio 2010. My question is whether this version of the package is too outdated compared to 2013. For now, I’m only…
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13
votes2
answers9163
viewsHow to force files of type . txt to be downloaded
I have a page, but I don’t want you to click on files like . txt to download instead of displaying them. I am developing this page in PHP. I saw some scripts on the web, but it is forcing the…
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answers73010
viewsI installed XAMPP but can’t start apache, Error: Apache shutdown unexpectedly
I installed the XAMPP on Windows and I’m not getting to start apache, the error I see is: 18:32:57 [Apache] Error: Apache shutdown unexpectedly. 18:32:57 [Apache] This may be due to a blocked port,…
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13
votes3
answers1792
viewsHow to create a solid mask from a semi-transparent Bitmap?
I want to create the image on the right from the one on the left. And I have the following structure: var Image, Mask : TBitmap; begin Mask := TBitmap.Create; Image := TBitmap.Create;…
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votes2
answers7627
viewsWhat is the C/C++ volatile modifier for?
I’ve seen in some codes on C/C++ statements like this: volatile int i = 0; I would like to know what the modifier is for volatile and in which cases should I use it.…
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answers2414
views#pragma Once or #ifndef?
I know there are two ways to prevent a header file from being duplicated in C C++: #ifndef FOO_H_INCLUDED #define FOO_H_INCLUDED class Foo { // código }; #endif And #pragma once class Foo { //…
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answers949
viewsHow does the Xor Swap algorithm work?
I was studying bit-by-bit operations and came across the Xor Swap algorithm. I understand what it does (exchange the value of two variables), but I don’t understand how it does it, at the level of…
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answers35893
viewsKeyboard buffer cleaning after scanf
I’m having trouble with the job scanf();. When reading two or more values, the later values are not read. I’ve already tried: __fpurge(stdin); After reading, but in this case I need to enter after…
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answers10996
viewsError while converting numbers. How to convert factors to numbers?
In the following example: dados <- data.frame(x=c("11", "10", "20", "15"), y=c("25", "30", "35", "40")) dados x y 1 11 25 2 10 30 3 20 35 4 15 40 When trying to transform the variable x number,…
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answers5462
viewsWhat is the lifespan of an SD card with Raspbian (Raspberry Pi)?
As all Raspberry Pi users should know, operating system runs from SD card. This can result in a problem, because if the card is written many times constantly, it will reduce SD lifespan for quite…