Recent questions tagged C++

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c++ - qt run shell commands via qprocess

I am developing a small QT application to interact with the terminal, to send commands to the terminal and to ... its information), Any advice? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Inaccuracy in gprof output

I am trying to profile a c++ function using gprof, I am intrested in the %time taken. I did more ... command. Waiting for your input Regards See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to interpolate a color sequence?

I need to interpolate or change gradually a sequence of colors, so it goes from colorA to colorB to colorC ... .normalize(); Thanks in advance See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - getchar() doesn't work well?

I wrote this code in C++, and I used getchar() to puase the console, but I did not see any effect of using ... +; address++; } return occ; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why can a non-const reference parameter be bound to a temporary object?

char f1(); void f2(char&); struct A {}; A f3(); void f4(A&); int main() { f2(f1()); // error ... I have submitted a bug report to VC++ team See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Subscripting a string literal

Is subscripting an alphanumeric a common/valid technique? And what are the implicit conversions that take place ? example ... here return 0; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - conditional debug output class with templated operator<<

I'm trying to create a simple qDebug-like class I can use to output debug messages in debug mode, dependant on ... need more info, please ask. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Ranking and unranking of permutations with duplicates

I'm reading about permutations and I'm interested in ranking/unranking methods. From the abstract of a ... unrank permutations with duplicates? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What kind of tree implementation is STL set?

I know that in STL vector represents the implementation of a dynamic array. So does the list represents the ... tree structure was chosen ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Range-based for loop and std::vector.push_back() crashing the program

#include <iostream> #include <vector> int main() { std::vector<int> vec; for (int i = 0; i < 42; ++i) { vec. ... = 0 and y == 22 on my computer. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - OpenCV compare two images and get different pixels

For some reason the code bellow is not working. I have two 640*480 images which are very similar but not ... is storing the current image. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Strange results with floating-point comparison

I have this simple test: double h; ... // code that assigns h its initial value, used below ... if ((h>0) ... ; if (h<1){ //computations here } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Optimising getting OR of Mat Channels

I want to to convert a BGR cv::Mat to gray using this formula Gray=B OR G OR R; pixel-wise operation ... ; pixel-wise operation any suggestion ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Force explicit template instantiation with CRTP

I am trying to use a CRTPed base to hold some static initialization code like this: template <typename T> class ... ++11 is not an issue. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Not sure how to build OpenCV for MinGW

TL;DR; I am trying to build OpenCV for MinGW. cmake keeps complaining about no sane CXX compiler, although I ... the tickbox "Alter PATH". See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Boost.x3: attribute accumulates between alternatives

I have a parser for parsing an Identifier like foo, bar, baz and one for parsing also nested identifiers like foo: ... and how I can avoid this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - std::vector calling destructor multiple times during push_back?

I'm pushing objects class tipo to a vector, when I push the first one the constructor get's called (as it ... ? Why could this be happening? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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287 views

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c++ - Fstream's tellg / seekg returning higher value than expected

Why does this fail, it's supposed to be simple and work ? fisier.seekg(0, ios::end); long lungime = fisier. ... , there are no extra spaces... See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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364 views

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c++ - Algorithm that can create all combinations and all groups of those combinations

Let's say I have a set of elements S = { 1, 2, 3, 4, 5, 6, 7, 8, 9 } I would like to create ... Qt 5.6, which is a C++ based framework. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - error: no matching function for call to

Heres my error... "In constructor 'NumGame::NumGame(int&)': error: no matching function for call to 'Category:: ... ::selection(int& b) { } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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196 views

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c++ - How to read a UCS-2 file?

I'm writing a program to get the infomation in *.rc file encoding in UCS-2 Little Endian. int _tmain(int argc, _TCHAR ... can I do it to UCS-2? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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299 views

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c++ - Boost Mutex implementation for Windows

As far as I know in old versions of Boost boost::mutex implementation for Windows was done using ... critical sections become deprecated? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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148 views

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c++ - Measuring time results in return values of 0 or 0.001

I am trying to use chrono::steady_clock to measure fractional seconds elapsed between a block of code in my ... This is a Windows program. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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258 views

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c++ - strncpy documentation question

At the following regarding strncpy: http://www.cplusplus.com/reference/clibrary/cstring/strncpy/, it mentions the ... meant by this sentence? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How could my code tell a compile-time constant versus a variable?

Here's my problem. I have a BINARY_FLAG macro: #define BINARY_FLAG( n ) ( static_cast<DWORD>( 1 << ( n ... compile-time constant or a variable? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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252 views

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c++ - Using cmake to build a static library of static libraries

I'm trying to create a static library of static libraries. Here's my CMakeLists.txt cmake_minimum_required(VERSION ... and one static library? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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312 views

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c++ - How to detect hot plugging of monitor in a win32 application?

I need some kind of event from Windows whenever there is a monitor that's getting plugged into system. Is there ... it is an C++ application See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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478 views

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c++ - Using const char* as key for map/unordered_map

How to create map/unordered_map that will use const char* as key directly? If I use map<std::string,.. ... char* directly without any overhead? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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