Recent questions tagged C++

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c++ - Implementing Qt project through CMake

I am trying to build and run very simple and basic example of Qt through Cmake, removing the .pro file. The ... h' no such file or directory. 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++ - array vs vector vs list

I am maintaining a fixed-length table of 10 entries. Each item is a structure of like 4 fields. There will ... before and after the operations? 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++ - What is the difference between a concrete class and an abstract class?

I am learning C++, but I am confused about abstract class and concrete class. Some real world examples would be 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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c++ - what does __declspec(dllimport) really mean?

I saw the Qt source code like this: class Q_CORE_EXPORT QBasicAtomicInt { public: ... }; Which ... __declspec(dllimport) really mean? 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++ - OSX - replace gcc version 4.2.1 with 4.9 installed via Homebrew

This has been plaguing me for awhile now. I am trying to compile a huge C++ file (I know it works ... random packages and the Standard Library 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++ - The Pimpl Idiom in practice

There have been a few questions on SO about the pimpl idiom, but I'm more curious about how often it ... thing would be welcome suggestions. 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 do I use CMake?

I am trying to use CMake in order to compile opencv. I am reading the tutorial but can't understand what is ... the end open with visual-studio? 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++ - Update GCC on OSX

So I am a new programmer and I just installed XCode on my Macbook to get the GCC. I think Xcode is the ... are the commands and stuff. 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++ - What does string::npos mean in this code?

What does the phrase std::string::npos mean in the following snippet of code? found = str.find(str2); if (found ! ... < int(found) << std::endl; 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++ - Converting from signed char to unsigned char and back again?

I'm working with JNI and have an array of type jbyte, where jbyte is represented as an signed char i.e. ranging from ... this in both C and 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++ - Test if a number is fibonacci

I know how to make the list of the Fibonacci numbers, but i don't know how can i test if a given ... simpler and faster method. 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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c++ - what is "stack alignment"?

What is stack alignment? Why is it used? Can it be controlled by compiler settings? The details of this question ... as avcodec.dll) Thanks, Dan 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++ - void_t "can implement concepts"?

I was watching the second part of Walter Brown's CppCon2014 talk on template metaprogramming, during which he ... something like Concepts Lite. 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++ - Will an 'empty' constructor or destructor do the same thing as the generated one?

Suppose we have a (toy) C++ class such as the following: class Foo { public: Foo(); private: int t; ... is one method preferred over the other? 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++ - When should I use C++14 automatic return type deduction?

With GCC 4.8.0 released, we have a compiler that supports automatic return type deduction, part of C++14. ... from which to answer 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++ - multiset, map and hash map complexity

I would like to know the complexity in Big O notation of the STL multiset, map and hash map ... entries retrieving entries comparing entries 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++ - Precompiled headers with GCC

Anyone had any success getting precompiled headers working with GCC? I have had no luck in my attempts and I haven' ... and using 4.0 on Ubuntu. 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++ - Building Qt5 with Visual Studio 2012 / Visual Studio 2013, and integrating with the IDE

How do you get Qt5 to download and integrate with Visual Studio 2012? What are some of the problems you ... with the Visual Studio IDE 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 can I access private variables in the copy constructor?

I have learned that I can never access a private variable, only with a get-function in the class. But then why can ... : T *pFirst,*pLast,*pEnd; 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++ - What is the preferred/idiomatic way to insert into a map?

I have identified four different ways of inserting elements into a std::map: std::map<int, int> function; function[ ... I have not thought of?) 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++ - Benefits of header-only libraries

What are the benefits of a header only library and why would you write it that way oppose to putting the implementation into separate file? 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 Creator - Project ERROR: Xcode not set up properly. You may need to confirm the license agreement by running /usr/bin/xcodebuild

I just installed Qt 5.5 and am using Qt Creator for the first time on OS X. When I first installed Qt, it ... there a way to fix this issue? 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 convert a char array to a string?

Converting a C++ string to a char array is pretty straightorward using the c_str function of string and then doing strcpy ... = "This is a test. 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++ - Advantages of std::for_each over for loop

Are there any advantages of std::for_each over for loop? To me, std::for_each only seems to hinder the ... coding standards recommend its use? 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++ - Circular lock-free buffer

I'm in the process of designing a system which connects to one or more stream of data feeds and do some analysis on ... making a few of my own. 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 use WinDbg to analyze the crash dump for VC++ application?

How do I use WinDbg for analyzing a dump file? 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++ - What is the difference between packaged_task and async

While working with the threaded model of C++11, I noticed that std::packaged_task<int(int,int)> task([](int a ... I use one over the other? 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::flat_map and its performance compared to map and unordered_map

It is common knowledge in programming that memory locality improves performance a lot due to cache hits. I recently ... cases for it? 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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