Most voted "c++" questions
C++ is a typed, compiled, multi-paradigm, intermediate level, and general purpose programming language. It should not be confused with the language C. It was developed in the early 1980s by Bjarne Stroustrup as an extension of C. Its evolutionary features include type checking, support for automatic resource management, object orientation, generic programming and treatment of exceptions, among others.
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answer736
viewsWhat are the practical differences in C and C++ code portability?
I have been reading some open-source C code lately and have noticed that many of them become quite complex and with enough #ifdef in order to make the code as portable as possible between different…
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answer270
viewsNot generating the 1000 random numbers needed
I am developing a C program that randomly generates a thousand numbers and that in the end appears the largest and smallest among them. For this, I am using the rand(). But I have a problem. When I…
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answer830
viewsERROR: This application is failed to start because it could not find or load the Qt Platform plugin "windows"
I am in error when running a program that was created with Qt , it generates the photo error! This error is generated when running exe, all the dlls indicated in the Walker dependency are in the exe…
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answers1517
viewsWhat to do when I get a bad_alloc error?
Before the question in question let’s assume a scenario: I have some program written in GTK+; The program uses the Operator new to allocate resources; (not to be confused with the Operator new…
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answer272
viewsInitialization of data of a class
Is there a class initialization function for C++? In Lua, using the library classlib there is the function __init, and in Python as well. EX: require "classlib" Human = class(); function…
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answer915
viewsAssign an expression to a variable
In c++ is it possible to execute expressions within a variable? Ex(in Lua): n = math.random(9, 10) a = n .. (#tostring(n) > 9 and "-" or "--") print(a) If n were equal to 9 it would return: 9--…
c++asked 10 years, 3 months ago Gabriel Sales 1,257 -
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answer91
viewsCode considered only at compile time can contain Undefined Behaviour?
When designing a function that adds up two values of any distinct classes, I can write the following in a generic way: template <typename T, typename U> decltype((*(T*)0) + (*(U*)0)) add(T t,…
c++asked 10 years, 2 months ago Guilherme Bernal 20,024 -
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answer686
viewsHow to train two objects with different sizes for recognition in Opencv
Hello, I am using Opencv version 2.4.11 to train license plate recognition for a parking software. The problem is when training to identify the car plate, truck, truck where the plates used by them…
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answer1276
viewsMulti Thread Socket Server - Java Server and C++ Client
I have to develop a Mini Server Socket Multi Thread (college work) in Java and need to make a Client in C, for example, can be in any language, but I chose these two. How do I send the Client values…
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answer316
viewsCapture joint position on X,Y,Z axes with Kinect V2
I need to extract the position of the joints from a recording and/or in real time, and convert to database format and/or file (txt). Similar to what is done in this video, but instead of displaying…
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answer2424
viewsFree up memory in C++
I am obliged to release memory of every variable that I will no longer be using? If yes, how to do?
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answer640
viewsWhat is the difference between a DLL produced with C++ and a C#
After some time searching, I did not find any results for this issue, the topics already existing in MSDN also returned nothing in relation to support of the 2 in Windows. In summary, the question…
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answers318
viewsError "Intellisense: 'No Additional information available'" in Visual Studio 2012
Today my computer crashed (because of Google Chrome! ) and I needed to restart it. Visual Studio 2012 was open at the time (and I lost a few lines of code that I hadn’t saved). The problem is that…
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answer1184
viewsGarbage Collector for C++
I clearly understand what a Garbage Collector is and what it is for. It is very well known in Java. Is there a C++ library that implements GC or fixes memory lLeaks? I’ve searched the internet but…
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answer179
viewsWhat are digraphs in C?
Based on the question of graphs, what are digraphs? Why were they created? What are the sequences? Current compilers still allow you to use them?…
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answers1071
viewsShow more accuracy in C++
I have this program: int main(){ double x=2; cout << sqrt(x); } I would like to show the result as accurately as possible. Thank you!
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answers1377
viewsHow to identify a USB device?
I have two types of devices (A and B) that communicate serial through USB and can be connected to the PC using linux. Is there a way to identify which device is connected without having to talk to…
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answer298
viewsWhat are the differences between Friend and Static classes/members?
What are the differences between classes and member variables friend and static within the definition of a class, including its applications. I only know which class members static belong to the…
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answer755
viewsHow to make an interface in C++?
Java, C# and other languages have the concept of interface, which is very useful in some circumstances. How to interface or get closer to it in C++?
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answers11601
viewsHow to calculate the Euclidean distance
I want to calculate the Euclidean distance by the following formula: So I tried, making this code: #define SLEEP_1 1000 void HeaderClass::DistanciaEuclidianaEntrePontos() { int x1, x2, y1, y2,…
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answer356
viewsWhat is * for in the expression "Foo* foo = new Foo" in C++?
I was looking into this question done in SOEN. There is teaching to instantiate a certain class. I was able to understand more or less how it works, because when I use my example, it is giving error…
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answers790
viewsLinux-based c++ Qt program to run on Windows
People wanted to know if there is any way and if there is what, to basically create an executable ,of a GUI program made in Qt, for Windows being that I am using Linux.
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answers194
viewsHow to read the command line?
Let’s say I want to do a routine to automate the process of compiling a program. In general (language independent), you call compiler from the command line. For example: javac meuPrograma.class or…
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answer1263
viewsHow to avoid buffer overflow in C/C++
The program below allows the occurrence of memory overflow, as it is possible to overwrite the variable zero, placing a value "large" in the variable buffer. How to make a safe program by avoiding…
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answer477
viewsTime difference between stdio. h and iostream
I made two codes so that an online Judge corrected. They are essentially the same. But the with stdio. h is accepted and the with the iostream is not, because it exceeds the time limit. Why this…
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answer1949
viewsWhat is the difference between Debug and Release?
I started having the error: "Microsoft C++ Runtime error library". And I got many problems trying to fix this error. I was using Qt Creator with mingw32 in mode debug, but I realized that this mode…
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answer155
viewsC++ overhead in method header
I’ve been analyzing the performance of a Directx renderer through the VS2015 Performance Profiler tool and it pointed me to an overhead in the header of a very requested renderer method, as shown…
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answer87
viewsDoubt Class C++
I would like to understand why some classes in C++ have the following statement: class Bla; class Ble { .... } My doubt is about the Bla class, it has no meaning as far as I could see.…
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answers142
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answers1478
viewsHow to verify the existence of a folder?
To verify the existence of a folder with a C/C++ program, it looks for the directory, if it does not find the specified directory, it will make the decision to create it.
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answer75
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answer90
viewsHow is it correct to declare a variable that is a pointer?
I see some people do int* variavel; And some people do int *variavel; What is right?
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answers606
viewsWhat is a tail recursion?
In that question I asked about performance. One of the users replied that the compiler does several interesting optimizations, such as inlining, Loop unwinding, tail recursion and caches. How Tail…
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answer282
viewsShould we disregard the return of functions in C that already receive the desired value by the parameter by reference?
Looking at the documentation of scanf() I saw that it returns a value, but I see the codes using it without using that return. This is right?…
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answers199
viewsIs there any difference between the ways of declaring classes in C++?
Ever since I started learning C++ I’ve always done something like: class. h #ifndef CLASSE_H #define CLASSE_H class OutraClasse; class Classe { public: Classe(); void foo(OutraClasse *bar); };…
c++asked 8 years, 5 months ago Guilherme Nascimento 98,651 -
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answers602
viewsDifference in C/C++ array declarations
What is the difference and impact that each of these 3 vector statements bring to my code? int n; cin >> n; int* arr = new int[n]; int n; cin >> n; int arr[n]; int n; cin >> n;…
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answers6106
viewsDifference from Cout to printf in C++
I wonder what difference I use in C++ cout and printf, it’s all the same?
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answer356
viewsReturn modified object
I have the following problem, as the didactic example below: #include "b.h" #include "c.h" class A { public: int start(); private: B b; C c; int x; } a.cpp int A::start() { c = b.copy(); x = c.d;…
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answers844
viewsSorting of object vectors
I am making an application that sorts an object vector. These objects are Cartesian points, defined in the following class: class CartesianPoint { private: int x; // Coordinate X of a pin or a wire…
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answer4920
viewsIs there a difference between using "Return" or "Exit()" to terminate the "main()" function?
The function exit() closes the execution of the application immediately. The command return makes you quit the function, but when you’re inside the main() will exit the application, including the…
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answers4614
viewsCharacter size (ASCII vs other encodings) in bytes
Seeing this issue a doubt arose, coming from PHP and in the past having "problems" derived from character encoding, ex: srtpos vs mb_strpos, i knew that all ASCII characters have 1 byte, but I…
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answer138
viewsWhy is Offloading for the GPU a good idea?
I follow some forums on the Internet and I realize that recently there has been much talk of holding Offloading tasks for the GPU. Mozilla has implemented a new engine for its browser called Servo.…
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answer298
viewsPerformance differences between structs and classes
I know the difference between structs and classes is that structs has its public members by default, and that structs belong to C (but nothing prevents use in C++). In practice when creating an…
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answer56
viewsWhen to choose between using a string wide or not?
When using a string wide (std::wstring) or a string normal (std::string)?
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answer142
viewsIs it worth using binary operators to gain performance?
I have the following situations: if (1 & 1){} and if (1 == 1){} According to what I’ve learned, working with bitwise Operators causes a much better performance in the program, with this I came…
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answers1725
viewsHow to increase number to fractional power?
I would like to know how to raise a number to a fractional power, for example 2^2.5, 3^0.7 ? For positive integers it works more or less like this : #include <iostream> #include <math.h>…
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answers957
viewsRandom numbers are always the same
Why is this code always displaying the same random number results of a given? // Figura 6.9: fig06_09.cpp // Lança um dado de seis lados 6.000.000 de vezes. #include <iostream> using…
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answers4160
viewsCopy from txt file to other
int main(void) { void copiaConteudo(FILE *arquivo, FILE *arquivo1); FILE *arquivo = fopen("tmp/exercicio.txt","r"); if (arquivo == NULL) { printf ("Não foi possível abrir o arquivo"); return 1; }…
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answers929
viewsWhat is the difference between expressions : "int a" and "const int& a" as C++ function arguments?
Let’s assume I have two functions: int soma_a(int a, int b){ return a + b; } and int soma_b(const int& a, const int& b){ return a + b; } What would be the difference between soma_a and…
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answer183
viewsWhy is there no "Logical XOR" in C++?
I was thinking and I came up with this question: Why is there "Bitwise OR", "Bitwise AND" and "Bitwise XOR", if in Boolean logic there is only "Logical OR" and "Logical AND". There should be the…