Recent questions tagged C++

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c++ - Why use base class pointers for derived classes

class base{ ..... virtual void function1(); virtual void function2(); }; class derived::public base{ int ... we can avoid base class pointers? 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++ - Massive CPU load using std::lock (c++11)

My recent efforts to implement a thread/ mutex manager ended up in an 75% CPU load (4 core), while all four running ... .join(); t1.join(); } 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++ faq - What does "cv-unqualified" mean in C++?

As from subject. I saw this terminology in a question I recently asked, and apparently it's a well ... to find anything on stackoverflow. 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++ - Dereference vector pointer to access element

If i have in C++ a pointer to a vector: vector<int>* vecPtr; And i'd like to access an element of ... the vecPtr 10000 ints be copied? 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++ - What's the difference between std::advance and std::next?

Is there more beyond advance takes negative numbers? 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++ - Modern way to filter STL container?

Coming back to C++ after years of C# I was wondering what the modern - read: C++11 - way of filtering ... to be defined are superseded by now? 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++ - Fastest way to scan for bit pattern in a stream of bits

I need to scan for a 16 bit word in a bit stream. It is not guaranteed to be aligned on byte or ... x86 machine code would all be interesting. 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++ - CMake: target_include_directories() prints an error when I try to add the source directory itself, or one of its subdirectories

I am writing a C++ library (header-only) and am using CMake to generate my (Visual Studio) project and ... finding a solution or explanation. 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++ - cmake - find_library - custom library location

I'm currently trying to get CMake running for my project (on windows). I want to use a custom location ... to handle multiple versions right? 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++ - C++11 Range-based for-loop efficiency "const auto &i" versus "auto i"

In C++11, I can iterate over some container like so: for(auto i : vec){ std::cout << i << std::endl; } But ... I'm using C++ in the fist place). 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 can a program with a global variable called main instead of a main function work?

Consider following program: #include <iostream> int main = ( std::cout << "C++ is excellent! ", 195 ); ... the program still compiles and runs. 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 do linked lists use pointers instead of storing nodes inside of nodes

I've worked with linked lists before extensively in Java, but I'm very new to C++. I was using this ... could help me understand that better. 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 is the effect of ordering if...else if statements by probability?

Specifically, if I have a series of if...else if statements, and I somehow know beforehand the relative ... issue of efficiency is moot. 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++ - Virtual Methods or Function Pointers

When implementing polymorphic behavior in C++ one can either use a pure virtual method or one can use ... disadvantages of each implementation? 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 are anonymous namespaces not a sufficient replacement for namespace-static, according to the standards committee?

According to this answer, namespace-scoped static variables were undeprecated in C++11. That is, they were ... a standards committee discussion. 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 call machine code stored in char array?

I'm trying to call native machine-language code. Here's what I have so far (it gets a bus error): char prog[ ... So what am I doing wrong 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++ - c++0x: proper way to receive a lambda as parameter by reference

What is the right way to define a function that receives a int->int lambda parameter by reference? void f(std ... to define a lambda parameter? 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++ - precise time measurement

I'm using time.h in C++ to measure the timing of a function. clock_t t = clock(); someFunction(); printf(" Time ... in C++ . I'm using VS2010. 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++ - Qt Slots and C++11 lambda

I have a QAction item that I initialize like follows: QAction* action = foo->addAction(tr("Some Action")); ... use lambdas to get the sender? 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 pretty-print STL containers in GDB?

I've followed the instructions on the GDB wiki to install the python pretty-printers for viewing STL containers. My ~/ ... comes with GDB 7.4. 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++ - Should a buffer of bytes be signed or unsigned char buffer?

Should a buffer of bytes be signed char or unsigned char or simply a char buffer? Any differences between C and C++? Thanks. 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++ - why do I need std::condition_variable?

I found that std::condition_variable is very difficult to use due to spurious wakeups. So sometimes I need to set ... I prefer choose it myself. 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++ - Why should I use asserts?

I never got the idea of asserts -- why should you ever use them? I mean, let's say I were a formula driver ... the way, I'm using unit tests. 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++ - Proper way to create unique_ptr that holds an allocated array

What is the proper way to create an unique_ptr that holds an array that is allocated on the free store? Visual ... 0x40075F: main (test.cpp:15) 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++ - Why does std::stack use std::deque by default?

Since the only operations required for a container to be used in a stack are: back() push_back() ... is still amortized constant anyways. 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++ - Using this pointer causes strange deoptimization in hot loop

I recently came across a strange deoptimization (or rather missed optimization opportunity). Consider this ... manual optimization technique. 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++ - Real life examples of xvalues, glvalues, and prvalues?

I was wondering if anyone could tell or explain some real life examples of xvalues, glvalues, and prvalues?. I ... when one should use them? 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 allocate thread local storage?

I have a variable in my function that is static, but I would like it to be static on a per thread basis. How can ... 0x and this is gcc v3.4.6. See Question&Answers more detail:os...

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

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