Recent questions tagged C++

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c++ - Why doesn't Python behave as expected when stdout and stdin are redirected?

I try to redirect in windows the cmd.exe stdout&stdin (with CreateProcess()). It works fine as long as I run simple ... (); system("pause"); } 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++ - Preprocessor variadic FOR_EACH macro compatible with MSVC++10

I've seen a few questions asking for a variation on a variadic FOR_EACH macro. However unfortunately the answers ... where x is another macro. 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 pass shared_ptr to class with lower lifetime?

I'd like to optimize my code. I have one class that has a shared_ptr data member. In some methods of ... What is the most standard solution? 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++ - Compile a C library with Visual Studio 2010

I got here a C library written by someone else, with a very nice way to compile it on a Mac and generate a ... to "fix" the project. Thanks ! 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++ - Compare floats to three decimal places

I wanted to know what would be the fastest approach of comparing floats to three decimal places.Say I have ... However it is returning true. 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++ - Determining the unique rows of a 2D array (vector<vector<T> >)

I am using a datatype of std::vector<std::vector<T> > to store a 2D matrix/array. I would like to determine ... ret.push_back(ulist[i]); } } 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++ - Does ZeroMQ have a notification/callback event/message for when data arrives?

I am trying to integrate ZMQ into an existing windows application that relies heavily on MFC sockets (CASyncSocket). ... off the ZMQ socket. 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++ - Optimizing a floating point division and conversion operation

I have the following formula float mean = (r+b+g)/3/255.0f; I want to speed it up. There are the following ... up with a mean between 0 and 1? 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++ - Inline constructors and One Definition Rule

Consider following source files 1.cpp #include <iostream> using namespace std; struct X { X() { cout << "1" < ... .0. How this can be explained? 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++ - cv::Mat conversion to Eigen-Matrix and back

I have several feature vectors stored in a cv::Mat where, each row is a feature vector (several rows like ... matrices are allowed. Thanks!!! See Question&Answers more detail:os...

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

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438 views

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c++ - Understanding 'most vexing parse' - why allow ambiguous syntax?

While trying to understand the "Most vexing parse" problem in C/C++, this question immediately springs to mind - ... as I find it clearer. 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++ - Program that modifes string inside its exe

I looking for example of program, that modifies a string inside its exe. I work with C++, Visual Studio under ... example to strTest = "foo")? See Question&Answers more detail:os...

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

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297 views

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c++ - Optimize Conditions

I've a simple question about conditions in if and for or while loops. Is there any way that lets me verify this ... I would like to be sure. See Question&Answers more detail:os...

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

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646 views

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c++ - Destructor is called when I push_back to the vector

I have this class definition: class FlashStream { public: explicit FlashStream(const char * url, vector<uint8> * ... .headers and NPStream.url? See Question&Answers more detail:os...

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

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530 views

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c++ - Custom folder icons with desktop.ini & instant refreshing

I am tasked with creating a book-keeping program that tracks some statistics of when files and folders are ... change folder icons immidiately? See Question&Answers more detail:os...

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

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477 views

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c++ - How do I declare template function outside the class declaration

#include <iterator> #include <map> #include <vector> template <class T1, class T2> class A { public: typedef typename ... Idea how to do 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++ - How to tell compiler to NOT optimize certain code away?

Is there a way to tell the compiler (g++ in my case) to not optimize certain code away, even if that code ... .h and others) will run slower. See Question&Answers more detail:os...

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

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394 views

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c++ - Template operator linker error

I have a linker error I've reduced to a simple example. The build output is: debug/main.o: In function main': C ... < std::endl; return *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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564 views

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c++ - How to disable the CListCtrl select option

I don't know how to disable the CListCtrl select option. I want to override the CListCtrl class method or handle any window command ? Thanks. See Question&Answers more detail:os...

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

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431 views

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c++ - eliminate unused virtual functions

To eliminate unused (ordinary) function I can use: -ffunction-sections, -fdata-section and --gc-sections. ... is mainly for learning purpose. See Question&Answers more detail:os...

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

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270 views

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c++ - Using boost::random and getting same sequence of numbers

I have the following code: Class B { void generator() { // creating random number generator boost::mt19937 ... I must be missing something. See Question&Answers more detail:os...

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

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417 views

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c++ - Is sparse BLAS not included in BLAS?

I have a working LAPACK implementation and that, as far as I read, contains BLAS. I want to use SPARSE BLAS and as ... printf(" "); 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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320 views

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c++ - Typedef a shared_ptr type with a static custom deleter, similar to unique_ptr

I have read through many questions on SO on custom deleter for shared_ptr and unique_ptr, and the difference between ... t possible". Why not? See Question&Answers more detail:os...

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

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710 views

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c++ - Aligning text in QTextEdit?

If I have a QTextEdit box, how can I align different pieces of text within the box in different ways? For ... I achieve this effect in Qt? See Question&Answers more detail:os...

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

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454 views

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c++ - Creating GDI+ bitmaps in memory and then saving as png

I am new to C++ and been having trouble with writing a function using the GDI+ library to create a new ... on this matter is much appreciated. See Question&Answers more detail:os...

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

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307 views

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c++ - Calling a function pointer whose assigned function has less arguments then the pointer type

Consider the following code: #include <iostream> typedef int (*test_func_t) (int, int, int); int print_integer (int ... with 1 or 2 arguments. See Question&Answers more detail:os...

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

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608 views

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c++ - Why is the downcast in CRTP defined behaviour

I have used the CRTP pattern for a while, however reading answers about undefined behaviour related to ... m simply misunderstanding CRTP. See Question&Answers more detail:os...

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

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277 views

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c++ - Any way to cast with class operator only?

Kind of a random question... What I'm looking for is a way to express a cast operation which uses a ... function... hence the question 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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