Recent questions tagged C++

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c++ - weak_ptr, make_shared and memory deallocation

A control block of a shared_ptr is kept alive while there is at least one weak_ptr present. If the shared ... and intent to use weak_ptrs)? 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 was the restriction on the comma operator being in a constant expression removed in C++11?

Recently when answering a question I realized that the comma operator is allowed in a constant expression in C ... was this restriction lifted? 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++ - Can't link program using Boost.Filesystem

I'm trying to run program, using sample code of boost::filesystem on Ubuntu 12.10, but it doesn't want to ... this problem and how to solve it? 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 can I find the minimum value in a map?

I have a map and I want to find the minimum value (right-hand side) in the map. Here is how ... require writing the additional compare function? 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++ - Trouble with template parameters used in macros

I'm trying to compile the following piece of code, I get an error on the line which specializes std::vector ... : http://codepad.org/qIiKsw4l 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++ - Two classes that refer to each other

I'm new to C++, so this question may be basic: I have two classes that need to refer to each other. ... there a better way to implement 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++ - How can I pass a part of a vector as a function argument?

I'm using a vector in a C++ program and I need to pass a part of that vector to a function. If it ... creating a new vector with the last part? 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++ - Can't use c++17 features using g++ 7.2 in QtCreator

I have recently updated gcc and g++ to version 7.2. I would like to try out std::experimental::any and ... effort of checking the docs for me. 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++ - MSVC equivalent of __attribute__ ((warn_unused_result))?

I'm finding __attribute__ ((warn_unused_result)) to be very useful as a means of encouraging developers not to ignore ... any luck so far.) 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++ - (Known) compiler bug in VC12?

This program, when compiled with VC12 (in Visual Studio 2013 RTM)[1] leads to a crash (in all build ... /i.stack.imgur.com/rrrnV.png 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++ - Non-type variadic function templates in C++11

I saw a blog post which used non-type variadic templates (currently not supported by gcc, only by clang). template <class ... 0) << 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++ - Bring window to front -> raise(),show(),activateWindow() don’t work

In my Qt-application I open a URL in the default-browser. Afterwards I want to bring the main-window ... which is derived from QDeclarativeView 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 can a 'const' method change?

C++ methods allow a const qualifier to indicate that the object is not changed by the method. But what does ... the content of the array. 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 memory sanitizer with libstdc++

I wish to use the -fsanitize=memory flag in clang to analyse a program like the following: #include <string> ... .5, stdlibc++ version 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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c++ - Why can't a forward declaration be used for a std::vector?

If I create a class like so: // B.h #ifndef _B_H_ #define _B_H_ class B { private: int x; int y ... were very enlightening in this matter. 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 are override and final identifiers with special meaning instead of reserved keywords?

Both the override specifier and final specifier were added in C++11. They differ from other specifiers added ... meaning instead of keywords? 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++ - Convert shared library to static library?

Is it possible to convert a shared library (someLib.so) to a static library? (someLib.a) 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++ - Documenting preprocessor defines in Doxygen

Is it possible to document preprocessor defines in Doxygen? I expected to be able to do it just like a ... ) the documentation of defines. 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 are Google Test, Death Tests

I saw the documentation of that feature is seem pretty major since it's in Google Test overview features and ... using those death tests are. 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 ## in a #define mean?

What does this line mean? Especially, what does ## mean? #define ANALYZE(variable, flag) ((Something.##variable) & ... the result be without ##? 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 functions default parameters

Could anybody explain where c++ compilers keep default values for parameters for virtual functions? I know it is a ... classes but why? 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++ - forcing use of cbegin()/cend() in range-based for

This question refers to: When should I use the new ranged-for and can I combine it with the new cbegin/cend? ... as a clue to detach itself. 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 a call to std::vector::clear() set std::vector::capacity() to zero?

If I use .reserve(items) on a vector, the vector will allocate enough memory for my guess of the number ... my earlier defined reserve? 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++ - Remove reference in decltype (return T instead of T& where T& is the decltype)

(If you're a C++11 pro, skip to the bold paragraph.) Let's say I want to write a template method which calls ... a better way, I'm feeling it. 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::map not have a const accessor?

The declaration for the [] operator on a std::map is this: T& operator[] ( const key_type& x ); Is there a ... a member map in a const method. 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++ - template metaprogramming: (trait for?) dissecting a specified template into types T<T2,T3 N,T4, ...>

I'm trying to deduce the underlying template type T from a type E = T<T2,T3>. This would for ... non-template arguments of unknown types. 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++ - Infix Calculator Expression Parser

How do I parse and evaluate expressions in an infix calculator grammar? I thought of two ways. The 1st involves using two ... && x == 2*x; } 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 add playable(such as wav,wmv) header with PCM data/buffer in iOS?

I am trying to add a wav header on top of raw PCM data to make it playable via AVAudioPlayer. But i ... highly appreciated. Thanks in advance. See Question&Answers more detail:os...

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

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