Posts by mgibsonbr • 80,631 points
861 posts
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3
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answer129
viewsA: Is jBCrypt still safe?
jBCrypt is simply an algorithm implementation bcrypt, so that if: There is no bug in this implementation (there is no bug report); and: No vulnerability has been discovered in this algorithm (it was…
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answers3787
viewsA: How to decompose a number into powers of 2
To response from Lucas Virgili explains well the reasoning behind the question (which is certainly even about binary representation), but I would like to give a somewhat more general answer: When…
javascriptanswered mgibsonbr 80,631 -
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answer19909
viewsQ: What are the advantages and disadvantages between Apache and Nginx?
I see a lot of people recommending Nginx on Apache [HTTP Server], and I can well understand why the first is Event-driven it brings advantages as to scalability (i.e. low memory consumption under…
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answers55
viewsQ: How to test virtual name-based Servers/SNI on a local machine?
I am migrating from Apache pro Nginx, and from a certificate "wildcard" (wildcard Certificate - a single certificate for several domains) for SNI. I would like to test the new configuration locally…
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answer5915
viewsA: Generic Tree, how to do?
First, if you need to store different types in a data structure, you must define a supertype for all of them. For example, instead of your node being a class, make it a generic interface: interface…
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answer133
viewsA: RSA, Sslstream - Key Exchange
I will answer in a very general way, because I have no familiarity with SslStream (or even C# in general), but I think there are some misunderstandings in this question that I can help clarify. The…
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answers375
viewsA: Join of SQL tables
Your problem seems to me to be in condition after the AND: it will only be true if there are non-zero values in the columns of R. Your Join is correct - were it not for this condition, every row in…
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answer677
viewsA: How do I create scheduled events in SQL Server, similar to Mysql’s "Event"?
The Mysql Event Scheduler is a Mysql-specific feature, which is not standardized for other DBMS (not part of SQL) and therefore cannot be directly ported to other platforms. However, there are…
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answer71
viewsA: Runtime calculation module(%)
In accordance with that answer in Soen, it is possible to calculate the quotient and the rest of a division with a single operation IDIV. That is, each of these 3 code snippets: // Trecho 1 var…
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answers14652
viewsQ: How to make the initial budget for a software project?
Context: I was "educated" in the methodology of Unified Process. I know Agile is very popular today, but I have very little knowledge of the process. I understand the philosophy that "changes are…
project-managementasked mgibsonbr 80,631 -
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answer287
viewsA: Performatively speaking, is it good to use Self Join?
I do not think there is any difference in performance between making a junction of one table with another, or a table with itself. I have no data to support this answer, except the absence of…
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answers3726
viewsA: What good is a "self Join"?
A use of the self Join that I consider "practical" (since its use to represent trees can be problematic) is to do competition control. As I detailed in another answer, Suppose you have a die that…
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answers1819
viewsA: Login using Entity with password encrypted as varbinary
Translated/adapted response of this reply in Soen What you need to do is encapsulate PWDCOMPARE in an UDF (user-defined function) in your database, and then call this UDF through your DataContext.…
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answer360
viewsA: Handling xml treat strings as if they were files
Many Python libraries expect files or "file-Likes" as parameters. Although this may seem restrictive, there is a built-in specific to treat strings as if they were files: StringIO (or its…
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3
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answers271
viewsA: How to allow only one instance of a certain class?
In the general case, one answer is to use Singleton, as pointed out by Diego Vieira in the comments. In your specific case, I believe that just change the behavior of the button to not create a…
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answers7017
viewsA: What is an abstraction?
Abstraction in computer science has its meaning derived from the same concept in philosophy, which is to "isolate one element to the exclusion of others". Its use is very similar to that done in…
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answers165
viewsA: What defines good logic?
Let’s assume that your logic or algorithm is quasi-optimal (i.e. mathematically speaking, there is no different procedure or proof to achieve the same result with a substantially smaller number of…
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answers13425
viewsA: What is an interpreted language? Is Java interpreted?
An interpreted language is one that needs a special program - called interpreter - for its programs to run. Contrast compiled language, in which your programs go through a process of translating…
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answers389
viewsA: *apply with three-argument functions in R
If you have a list, and want to call a function using the elements of this list as parameters, you can use do.call: minhafuncao <- function(a, b, c) { return(a * b + c) } minhafuncao(1, 2 3)…
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answer10018
viewsA: What is the difference between Javabean and POJO?
POJO - Plain Old Java Object - is simply a name given to a "normal" object with nothing special. It has its fields, its methods, its builders, etc, but does not follow [necessarily] any…
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answers318
viewsQ: Is referring to an element via its id considered bad?
In Javascript, you can refer to any element that has a id (and in some cases a name) using simply an identifier with the same name - without the need to declare it: <div…
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answers533
viewsA: Difficulty with web scraping
I’m assuming you’ve already got a reference to the element <a> desired, and can also extract the content of the attribute href (if I’m wrong in these assumptions, add more details to the…
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answers3635
viewsA: What is metaprogramming?
To reply from Guilherme Oderdenge demonstrates well the concept of metaprogramming: "programs that create programs". In my reply, I will give a more practical approach (rarely does anyone write a…
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answer15547
viewsA: How is 'super' used in Python classes and what is it used for?
The super serves to - in an inheritance relationship between a class Base and another Derivada - allow the class Derivada refers explicitly to the class Base. Suppose the following classes: class…
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answers1149
viewsA: What are the metaclasses?
A metaclass is the class of a class. What is a class? At first, we could create objects directly, without intermediaries: just define an object X, give him a set of properties A, B, C and a set of…
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answers8167
viewsA: When to use recursion and when to use loops?
I agree with the answer of utluiz, I would just like to add the following: Whereas a programming language being used has both features... Possess the two resources are not enough, it is also…
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answers2199
viewsA: Exception in thread "main" java.util.Nosuchelementexception
Are there empty lines in your file? (the last maybe) A documentation of getDouble says: Nosuchelementexception - if the input is exhausted I notice you do trim on the line and proceed to the reading…
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answer652
viewsA: Rsacryptoserviceprovider - Decrypt
RSACryptoServiceProvider does not support 128 bit keys: Support key sizes of Rsacryptoserviceprovider 384-bit to 16384-bit increments in 8-bit increments if you have the enhanced Microsoft…
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answers104158
viewsA: How to solve a Notice: Undefined index?
This error indicates that there is no value in your variable $_POST with the name "submit". Either your form did not include this field, or the request is not a POST (I’m not sure about this second…
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answer451
viewsA: Web Sql - Make select from ID
By an accident of your own se_id is numerical? When you do: var myTest = document.getElementById("list").value; The value of myTest is a string. Use it in select will cause it to return no result if…
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answers5635
viewsA: Make a regex to remove characters
Regex in this case is Overkill... Simply use substring: var entrada = "/Date(1401731794773)/"; var conteudo = entrada.substring(6, entrada.length-2); This is possible in this case because both…
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answer698
viewsQ: Does Prolog have static or dynamic typing?
Although I’m quite familiar with the concept of static vs. dynamic types - can easily recognize if a certain language fits in one or the other - I never knew exactly what the Prolog typing is:…
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answers33467
viewsA: What is the difference between a static and dynamic programming language?
What is the difference between static and dynamic language? There is no concept of "static language" or "dynamic language". What the original article in English speech - and that the Portuguese…
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answer433
viewsA: Draw Regular Polygons inscribed in a circle with Canvas in Javafx
The methods Math.sin and Math.cos accept parameters in radians. You’re passing them on degrees. In your first code this is taken into account: double anguloRadiano = Math.toRadians(angulo); But not…
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answer193
viewsA: When is it useful to capture DOM events?
I believe this is useful to give the elements Parent the "final word" about the events that occur in your children. This allows decoupling a common, generic functionality that needs to be…
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answer99
viewsQ: How to create a "Glass pane" in Javascript?
I’m trying to create a "Glass malfunction" in Javascript, similar to supported by Java. The goal is to offer a kind of interactive help to the user, where information about each element is…
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answers124
viewsA: How to use FOR-generated number in the name of a variable?
To bfavaretto response is the most recommended, but in case you need include the numeric index in the variable name for some reason, you can use any object (including the global object window) and…
javascriptanswered mgibsonbr 80,631 -
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answer163
viewsA: Javascript compression techniques and tips
Not "Compile your code by hand"! Remember that "programs should be written for people to read, and just by chance for machines to run." The reason why people use Javascript mini-protectors (or…
javascriptanswered mgibsonbr 80,631 -
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answer3396
viewsA: Java Regular Expression
When you wear brackets in a regex, you’re asking her to marry one and only one character from the list indicated. Except for the special characters (-, \ and ^ [at the beginning]), everything inside…
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answers8116
viewsA: Why and when to use XML instead of JSON?
The decision between using XML or JSON is more or less like choosing between a relational database or a Nosql: it all comes down to deciding on a explicit scheme or implicit. A schematic (schema) is…
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answer5160
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answer3364
viewsA: Validate decimal numbers in Javascript
I believe it would be through the use of a regular expression. An expression that satisfies all your proposed tests would be: ^-?\d*\.?\d+$ Example in jsFiddle. Explaining: ^ string start -? with or…
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answers18353
viewsA: Why is COBOL still the preferred language in the business world?
A banking institution needs to process an immense amount of data daily, cannot afford the system to be "off the air" from time to time, and needs a correct answer for complex calculations in a…
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answers265
viewsA: W3C HTML validator accuses "Empty Heading"
The meaning of "Empty" in this case is not that the tag has no content; it is that this tag does not refer to a section. The semantic meaning of a header is that it is "the header of a section", and…
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answers7447
viewsA: How to prevent spam in contact forms without using CAPTCHA?
One way is to use a proof of work (Proof-of-work system), such as the Hashcash or the virtual currency mining system Bitcoin (among others). A simple example would be: Choose an integer number T to…
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answers3857
viewsA: Django - How to redirect the user to the other pages of the application?
In principle, you could use absolute (or even relative) paths instead of complete Urls. In this way, the link would lead to a path within your domain, whatever it is: /cadLivro/ cadLivro/ If you are…
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answer386
viewsA: How to limit to 1 the keydown event in Jquery?
Your problem is that you’re in progress, assigning a Handler new to keyup to each animation board. This means that the moment a key is pressed, hundreds of identical copies of your code will run,…
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answer778
viewsA: Django - How to distinguish which button was clicked?
To my knowledge, if you have several buttons in the same form you can not submit this form to different pages unless you use Javascript to change the action of form. What you can do is have a…
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answers16863
viewsA: Cross-browser way of copying text to the Clipboard (Clipboard)
In my particular case, there is no need to create a new ClipboardEvent, because I am dealing precisely with an event of copy or paste. In this case, just locate the original event, and assign the…
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answers16863
viewsQ: Cross-browser way of copying text to the Clipboard (Clipboard)
I’m looking for ways to copy a text to the clipboard (Clipboard) via Javascript, which works on most modern browsers, but there is too much information and seems to me outdated. I know there is a…