Recent questions tagged C++

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c++ - Is it allowed for a compiler to optimize away a local volatile variable?

Is the compiler allowed to optimize this (according to the C++17 standard): int fn() { volatile int x = 0; ... ? If not, which step is invalid? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to enable C++17 in CMake

I'm using VS 15.3, which supports integrated CMake 3.8. How can I target C++17 without writing flags for each ... is only available with C++17. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Implicit conversion not happening

The last question I asked was something I stumbled upon when trying to understanding another thing... that I also can ... reading up to here :) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - OpenCV Transform using Chessboard

I have only just started experimenting with OpenCV a little bit. I have a setup of an LCD with a static position, ... write them to file), etc? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Storing multiple messages in one protocol buffer binary file

I have repeating messages which I want to store in a single file. Currently I have to wrap this repeating message ... repeated Box boxes = 1; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - boost::asio threadpool vs. io_service_per_cpu design

Currently I′m not sure, I try to make a high-performance server, I got a 6Core CPU, so if I would use ... test with each, or something else? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Const method that modifies *this without const_cast

The following pattern has arisen in a program I'm writing. I hope it's not too contrived, but it manages to mutate ... legal?? return data; } }; See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - QThread emits finished() signal but isRunning() returns true and isFinished() returns false

Below is the code for my qthread implementation. I am trying to get gps data from satellite. QThread doesn't ... ; networkThread->start(); } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Templates don't always guess initializer list types

#include <initializer_list> #include <utility> void foo(std::initializer_list<std::pair<int,int>>) {} template < ... than long and ugly casting? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Win32 - Get Main Wnd Handle of application

I have injected my dll into process. How can I get Main window handle of host application? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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250 views

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c++ - QApplication In Non-Main Thread

I need to exec() a QApplication in a thread that is not main (my GUIs must be plugins that can be dynamically loaded ... in C++ using gcc4.3.4. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to create a virtual file?

I'd like to simulate a file without writing it on disk. I have a file at the end of my executable and I ... work and be a much easier solution. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Compile time string encryption using constexpr

I want to have a compile-time string encryption, such that I could write in my code: const auto ... plain text to the binaries. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to do AES decryption using OpenSSL

I'd like to use the OpenSSL library to decrypt some AES data. The code has access to the key. This project already ... where do I get it from? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ cli - Convert from C++/CLI pointer to native C++ pointer

I have run in to this problem of converting a C++/CLI pointer to a native C++ pointer. Heres the ... an interior_ptr. Any ideas in this? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Win32 SetForegroundWindow unreliable

I have a rather complex series of applications which depend on the ability to switch applications in the ... or advice is appreciated. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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194 views

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c++ - Creating a lock that preserves the order of locking attempts in C++11

Is there a way to ensure that blocked threads get woken up in the same order as they got blocked? I ... But these problems are almost alike. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Forcing Machine to Use Dedicated Graphics Card?

I am part of a team developing an application using C++ with SDL and OpenGL. On laptops when the application is ... a solution that'd be great. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - search 25 000 words within a text

I need to find occurrences of ~ 25 000 words within a text. What is the most suitable algorithm/library for this purpose? target language is C++ See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Bytewise reading of memory: "signed char *" vs "unsigned char *"

One often needs to read from memory one byte at a time, like in this naive memcpy() implementation: void *memcpy( ... an uint32_t in a char[4]. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Qt 4.x: how to implement drag-and-drop onto the desktop or into a folder?

I've written a little file-transfer application written in C++ using Qt 4.x ... it logs into a server, ... or higher) would suffice. Any ideas? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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457 views

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c++ - Preventing non-const lvalues from resolving to rvalue reference instead of const lvalue reference

I'm having trouble overloading a function to take a value either by const reference or, if it is an rvalue, an ... // void bar(vector<int>&&) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Amortized analysis of std::vector insertion

How do we do the analysis of insertion at the back (push_back) in a std::vector? It's amortized time is ... 5. How is this constant determined? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ linux double destruction of static variable. linking symbols overlap

Environment: linux x64, compiler gcc 4.x Project has following structure: static library "slib" -- inside this ... ) this=6296204, is Dead See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Virtual destructor: is it required when not dynamically allocated memory?

Do we need a virtual destructor if my classes do not allocate any memory dynamically ? e.g. class A { private: ... A's destructor as virtual ? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Visual studio 2015 gives me errors upon creating a simple test console program

Here is the code I am using. #include "stdafx.h" #include <iostream> int main() { std::cout << "hi"; return 0 ... why. How can I get them back? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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315 views

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c++ - Initialize std::array with a range (pair of iterators)

How can I initialize an std::array from a range (as defined by a pair of iterators)? Something like this: ... constructing it first. How can I? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - C++11 random numbers

I need to generate random numbers, but from as wide a range as possible (64 bit at least). I don't care if ... as possible (like std::rand())? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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