Posts by Maniero • 444,682 points
6,921 posts
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answer257
viewsA: Vector and strcpy problems in C language
There are several errors there and this code doesn’t even compile, come on: Missing include the header string.h to use the function strcpy(). Is declaring a string 22 valid characters and not 23…
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answers1299
viewsA: Should every table have Primary key?
Unfortunately, there’s a little bit of a bad decision there for choosing to use a technology that is virtually abandoned (perhaps choice of course). Nothing critical because it is something for a…
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answer62
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answer348
viewsA: Try/catch on switch creating infinite loop on run
The code is confusing and so it is even difficult to find the error, and easy to make it. It’s too big a method with too much code repetition, but I’m not gonna try to fix it. At least keep things…
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answer68
viewsA: What is the risk of an error on an already loaded page?
We must always eliminate mistakes no matter how visually everything is "right"? It’s not all right, it’s all working, it’s different things, so you have to do it right, because what’s wrong one day…
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answer394
viewsA: Add 2 attributes and return to a third attribute
I see some problems in this code, all conceptual. What you call an attribute is actually called a field. Hey I know, there’s plenty of place teaching wrong, it’s not your fault. This code should…
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answers891
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viewsA: Programmatically or in XML layout
In general it is like, but you can say that the imperative code (what you are calling programmatically) will always be more flexible or powerful, unless the technology has a lot of "magic", and even…
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answers281
viewsA: Class that implements two interfaces that have identical signature methods
Your remark about contracts is correct, you have only one contract, but then it is not correct that there will be invocation of the method of one of the interfaces, there is no method in them, only…
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answer1245
viewsA: How to initialize an Arraylist in the constructor?
There are some weird things in this class. The first is to call the super()in a class that inherits nothing but Object, can already say that this is not necessary, after all the builder of Object…
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answers1649
viewsA: What is the underscore (or underline _ ) for in the repeating structure?
The _ suggests by convention that wants to discard the value that would normally be stored in a variable. In this case you are taking a track counting up to 3, but you do not want to use this value…
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answer897
viewsA: Create tuples with random values
You’re using the literal form of a tuple, you need to use the creation function of a tuple, then you can use the for normally: from random import randint tupla = tuple(randint(i + 1, 9) for i in…
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answers177
viewsA: What is the difference between these two Boolean expressions?
It is a matter of operations precedence, as occurs in mathematics (multiplication and division always occur before addition and subtraction unless there is something grouping them together, such as…
boolean-algebraanswered Maniero 444,682 -
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answer63
viewsA: A table just to store images or split by types?
This shape can be interesting in most cases as optimization. In general you need the user data in various contexts but not the photo, so it may be that having only the data can read several of them…
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answer350
viewsA: How to concatenate a variable plus a message in the "Insert"?
Yes, have, you need to use a function for this, in case it is the CONCAT(). Then it would look something like this: insert into tb_usuario values (concat('a', 'fez tal coisa')); Although this case…
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answer44
viewsA: Why can’t "If" verify equality between Ctype(double, int32) with int32?
This is because the type Double has no accuracy and to be equal needs to be exactly equal, a minimum difference is not acceptable, it is already different. You can see more details on What is the…
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answer213
viewsA: Double type variable precision problem
The problem is in What is the correct way to use the float, double and decimal types?. Since you will not use a more suitable type in an exercise the solution is to equalize everything to integer,…
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answer99
viewsA: "For" 'lagando' interface
Javascript has strings immutable, then incurs the problem called Shlemiel the Painter’s Algorithm. I’m not saying this is the only problem, but it makes everything terrible, and I think this way can…
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viewsA: Why does the code return Nan Hi BMI calculation?
There are some problems with the code. First is declaring and initiating the variables outside the function, this makes no sense, besides being bad to maintain global scope ends up running at…
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answers871
viewsA: Use more than one language in the same project?
I already answered that in How to use multiple languages in a single program?. But speaking specifically to what you have been asking, it is OK to use more than one language in a solution, you make…
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answers84
viewsA: How to get the name of a variable as a string in Go?
There is nothing like nameof of C#, including because this operator does not exist to do what you want, it is a way to avoid silly maintenance errors when changing the variable name. It would be…
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answer148
viewsA: Pair or odd loop does not show the expected result
The problem is that this multiplication that adopts a factorial pattern will generate a very large, very large number. It does not fit in a int, or even a long, needs a BigInteger to make it work,…
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answer65
viewsA: I want to save 3 numbers and then print on the screen
There’s a ; where you shouldn’t be there, you’re shutting down the fordoing nothing (it closes in the ; without having a block to execute), there opens a single block isolated, without belonging to…
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answer253
viewsA: Build a knot tree
Your problem has nothing to do with object orientation, it’s just a simple imperative algorithm that is wrong. At least the main focus. In the original question had not that want the whole solution,…
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answer473
viewsA: How to concatenate the name of a variable into C++?
You want to wear a array, or in C++ probably a vector will work better, so you have the variable divided into two parts, a wider variable that contains a whole collection of other variables and will…
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viewsA: Have more than one line in the same query
The same way you used a AND, just use a OR when you want one or the other. But more than learning how it does my suggestion is to study relational logic. SELECT * FROM `app_product` WHERE…
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answer301
viewsA: Create and implement Exceptions in PHP
Exception is something overrated. They are less useful than people think and almost everyone uses wrong. I talk about it a lot here on the site. In PHP, a language of script, it makes even less…
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answers56
viewsA: Widening conversions and option Strict on
This example would have no loss, this conversion is the call widening, then he’s taking something narrow and making it wider. You take something that exists in the other kind. Accuracy is detail,…
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answer332
viewsA: Sum of digits of a string only works when I do a subtraction I don’t understand
You’re getting a guy char which for all intents and purposes is an integer, but it is not a digit. It can be used to print any text, but it is a number. It just has to special that a text of a…
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viewsA: Equals() and Hashcode() superscript
Eclipse just generates code for you, nothing more than this, whoever overrides it is the compiler. Read more in What is a programming language, IDE and compiler?. What you call an attribute actually…
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answer88
viewsA: Sparsearray vs Hashmap what’s the difference?
It is an optimization of HashMap. Java works with everything based on reference types that generate allocation, and portando occupy more memory and pressure ni Garbage Collector. Still bad for the…
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answer200
viewsA: Is a Python dictionary as efficient as a tree or a hash?
The internal implementation of the Python dictionary is using tables hash, then has complexity O(1) to find keys, this can be confirmed in official Python wiki (thanks to Alexciuffa). It is, in…
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answers101
viewsA: What reason does the "missing()" at the end of the program send me an error in which it is not possible to compile?
Actually the code has several problems, including conceptual ones, but for a very basic exercise only of mechanisms most are not a big problem. It also has problems of organization and naming names…
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viewsA: Using && e || instead of "if" and "Else"
What’s the name of it? Conditional expression. Just this. It does not replace the if and else since these commands are imperative flow control, they do much more than is occurring there. This same…
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answer81
viewsA: Can’t find one string inside the other
The main problem is of algorithm itself. The loop does not make the slightest sense in the written form. There is also a syntax error in the code and so it does not compile and is poorly organized.…
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answer149
viewsA: What is the difference between memmove and memcpy?
The name memmove() gives a slightly wrong idea since it copies the same memcpy(), so if you really want her to move, you’ll need to delete the previous one on your own. Almost always use the second…
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viewsA: Add value to my contact for each multiples of 200 without having to create individual variables
There are too many variables there. You could use the conditional operator instead of the if. I could simplify a little more, but in the background it would be worse, so I left it so. I also…
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viewsA: I’m trying to do a research boot on my view, but tell me it can’t be null
The mistake is certainly here: return View(movies.Where(x => x.MovieName != null && (search == null || x.MovieName.StartsWith(search))).ToList()); I put in the Github for future…
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answer131
viewsA: What is the name given to an unsigned "overflow"?
I do not know any specific official term, there uses a very common expression that is "wrap Around". In fact, what occurs with non-flagged types in C can even be called overflow, even by virtue of…
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viewsA: Build error in C++
The code has a lot of errors, and although it will be able to deliver the work it does not seem that you will be learning to solve what comes up and this will bring you problems in the future. A lot…
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answer92
viewsA: Accessing a function variable
In C, I can use a variable outside the scope where it was declared? No, the variable only exists in the scope that has been declared. I know that the best thing to do is to declare her out of any…
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viewsA: How do I create an Arraylist of objects with each position containing a new object?
You should not do so. The code compiles and executes, but this form is considered wrong. The class calls Produto, So what do you expect to have in it? A product, right? Why do you find a list of…
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answer5166
viewsQ: What are the reasons to choose between camelCase and Pascalcase in method names?
First, I’m not interested in what you like best or what you use in your language, I want to know the motivation to choose one or the other pattern in a hypothetical language. Second, this is a bit…
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viewsQ: What is a business rule and an enforcement rule? What defines a mechanism as one or the other?
I know that has question about it in general. But I want to be specific. When creating a business class, a Cliente for example, it makes sense to have parts of the mechanism, such as Object (I know…
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answers189
viewsA: Function to print the number of characters in a two-dimensional string
You can simplify the code well and avoid some errors. In addition to not using a function that is inappropriate for reading data. But what’s complicating it is that you’re creating a array in the…
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answers90
viewsA: Exit error while trying to print contents of.txt file
Do you really need this abstraction for the dice? The main reason for the problem in the code that causes the described error is the lack of memory allocation to store the data. There is also an…
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