Recent questions tagged C++

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c++ - C++11: Move/Copy construction ambiguity?

In C++11 we can define copy and move constructors, but are both allowed on the same class? If so, how do you ... ? A move? How do I know? 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++ - Is it necessary to lock an array that is *only written to* from one thread and *only read from* another?

I have two threads running. They share an array. One of the threads adds new elements to the array ... someone starting out with multithreading. 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 undefined are __builtin_ctz(0) or __builtin_clz(0)?

Background For a long time, gcc has been providing a number of builtin bit-twiddling functions, in particular ... to separate such platforms? 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 create a shared library (.so) in an automake script?

Given some source file test.cpp I would like to create a shared library libtest.so . I am trying to do this ... an .so based on the above? 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 signals and slots: permissions

There are discrepancies between respected answers here on SO and the actual Qt docs. I've read this question and ... i.e. SomeClass::itsSignal) 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++ - Do we need to use std::launder when doing pointer arithmetic within a standard-layout object (e.g., with offsetof)?

This question is a follow-up to: Is adding to a "char *" pointer UB, when it doesn't actually point to ... -C++17 usages of offsetof undefined. 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++ - Partial match for the key of a std::map

I have an std::map and I want to search for a key using a substring. For example, I have the following ... t want to use any Boost libraries! 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 cannot find GoogleTest required library in Ubuntu

Similar issue here. This is my CMakeLists.txt: cmake_minimum_required(VERSION 2.6) # Locate GTest find_package(GTest ... cmake-gui. What gives? 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 assembly from array 0-initialization

Inspired by the question Difference in initalizing and zeroing an array in c/c++ ?, I decided to actually examine ... to strb) is used. 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++ - gcc 4.9.1 in OS X Yosemite - gcc: warning: couldn’t understand kern.osversion ‘14.0.0'

I install OS X Yosemite and now i have a huge problem with gcc 4.9.1 compiler. I hope some one can help ... wrong folder? Anyone can help me? 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 get array of bits in a structure?

I was pondering (and therefore am looking for a way to learn this, and not a better solution) if it is ... } bit; properly using #pragma pack 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 wasn't yield added to C++0x?

EDIT, 11 years after I asked this question: I feel vindicated for asking! C++20 finally did something ... Simple transformation? Arguably, yes. 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++ - Calling template function within template class

Disclaimer: The following question probably is so easy that I might be shocked seeing the first answer. Furthermore, ... how obvious they are. See Question&Answers more detail:os...

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

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300 views

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c++ - Overhead of pthread mutexes?

I'm trying to make a C++ API (for Linux and Solaris) thread-safe, so that its functions can be ... ways to protect such variable accesses? See Question&Answers more detail:os...

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

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285 views

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c++ - std::pair<int, int> vs struct with two int's

In an ACM example, I had to build a big table for dynamic programming. I had to store two integers in ... explains this huge difference in time? 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++ - Most efficient standard-compliant way of reinterpreting int as float

Assume I have guarantees that float is IEEE 754 binary32. Given a bit pattern that corresponds to a valid ... will guarantee single load/store? 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++ - Slicing a vector

I have a std::vector. I want to create iterators representing a slice of that vector. How do I do it? ... the elements to a new datastructure. 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++ - Can I selectively (force) inline a function?

In the book Clean Code (and a couple of others I have come across and read) it is suggested to keep the ... of several calls to other functions. 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++ - When to use C float comparison functions?

In the latest C++ standard, I noticed the following macros : bool isgreater(float x, float y); bool isgreaterequal(float ... ) << std::endl; } 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 initialize a shared_ptr that is a member of a class?

I am not sure about a good way to initialize a shared_ptr that is a member of a class. Can you tell me, whether ... boost::shared_ptr<B>(pb); } See Question&Answers more detail:os...

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

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300 views

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c++ - C++11 alternative to localtime_r

C++ defines time formatting functions in terms of strftime, which requires a struct tm "broken-down time" record. However, ... .call( t, r ); } 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++ - Use data type (class type) as key in a map

I have class Base and classes Derived_1, Derived_2 ... I need derived classes to have an id. Those ids are ... some of yours answers, thank you 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++ - Is it ok to call a function in constructor initializer list?

My gut feeling is it is not. I am in the following situation: class PluginLoader { public: Builder* ... from where PluginLoader is constructed? 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++ - Visual Studio: project is not up to date "because "AlwaysCreate" was specified"?

I've migrated a solution from VS2008 to VS2010 (SP1). Now one of my project never finds peace in being up-to-date. ... ========== Any ideas? 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 IPC method on Windows 7

What is the fastest possible Interprocess Communication (IPC) method on Windows 7? We would like to share only a ... Boost library use for IPC? See Question&Answers more detail:os...

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

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576 views

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c++ - Is it more efficient to preallocate a vector?

In C++ Primer fourth edition, by Stanley B.Lippman, Josee Lajoie and Barbara E. Moo it states: Because ... this statement, and explain why? 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++ - Initialisation of static vector

I wonder if there is the "nicer" way of initialising a static vector than below? class Foo { static std::vector ... , tell me that also :) 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 doesn't a const reference extend the life of a temporary object passed via a function?

In the following simple example, why can't ref2 be bound to the result of min(x,y+1)? #include <cstdio> ... y+1); ^ Compiler returned: 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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