Recent questions tagged C++

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c++ - Move constructors and the Strong Exception Guarantee

Just a quick question, on which I cannot find a good reference, especially with regard to current implementations ... what has been discussed. 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++ - to system() or fork()/exec()?

There appear to be two common ways of running an external executable from C in unix, the system() call and ... is returned from child)?. 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++ - glReadPixels() "data" argument usage?

I'm trying to use glReadPixels to get color data from an image. I'm supposed to be using glReadPixels but I can't ... , or how to get the color) 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++ - anonymous namespaces and the one definition rule

Am I violating the One Definition Rule with the following program? // foo.hpp #ifndef FOO_HPP_ #define FOO_HPP_ ... foo() is identical. 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 Standard Library (STL) Containers support a form of nothrow allocation?

The new operator (or for PODs, malloc/calloc) support a simple and efficient form of failing when allocating ... -reserve also would have. 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++ - std::function with non-static member functions

i'm trying to understand a concept and an error. what's wrong with this? class A { public: A() { std: ... them, i would greatly appreciate it. 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++ - Overloading unary operator &

Let's consider a class with overloaded unary operator & (Address-of). Let it be class A template <class C> ... Or there are some other reasons? 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++ - Which boost libraries are heading for TR2?

If found this quote at boost.org: More Boost libraries are in the pipeline for TR2 It links to the TR2 ... documented something about the TR2. 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 different between visual studio F5, ctrl+F5, or running outside of visual studio?

I have written a program in vc++ that has different behavior in various case as below. When I run it ... what is different between these cases? 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++ - using C++11 attributes

Could you please explain how to get information from attributes in C++? For example, I want to write C++ to ... as in Java or C# annotations? 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 `type_info::before` useful for?

According to cplusplus.com, the std::type_info::before() function... Returns true if the type precedes the type of ... So what is it useful for? 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++ - vtable for .. referenced from compile error xcode

I was getting the following error compiling an iPhone project: "vtable for oned::MultiFormatUPCEANReader", referenced from: ... I may fix it? 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 Write the Range-based For-Loop With Argv?

From the c++0x Wikipedia site: int my_array[5] = {1, 2, 3, 4, 5}; for (int &x : ... 0x Range-Based For-Loop Statement Definition Redundance 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 happens if I capture a local variable by reference, and it goes out of scope?

Suppose I use a lambda as a callback function, and when creating the lambda, I capture a local function variable by ... would end up doing it. 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 is there no std::make_function()?

std::function<> is a useful wrapper around almost any callable thing, including free functions, lambdas, functors ... first question remains.) 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++ - Concatenating two QStrings with an integer

I want to do something like this in C++ using Qt: int i = 5; QString directory = ":/karim/pic" + i + ". ... karim/pic5.jpg). How can I do this? 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 possible to enable array bounds checking in g++?

Is it possible to have g++ show an error when compiling the following file with some flag? #include <iostream> using ... works with C, not C++. 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 implicit conversions with the ternary operator

I have the following code: class A { public: operator int() const { return 5; } }; class B { public: ... is correct in this case, and 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++ - Force to link against unused shared library

Moved from gcc 4.5 to gcc 4.6, and now it does not link against libraries that are not used at compile ... with all libraries listed via -l? 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++ - Existence of objects created in C functions

It has been established (see below) placement new is required to create objects int* p = (int*) ... a trivially default-constructible object 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 proper use case for dynamic_cast?

I have been told many times (and seen myself in practice) that the use of dynamic_cast often means bad ... use of dynamic_cast is justified? 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++ - Implicitly treating returned lvalue as rvalue

12.8 Copying and moving class objects [class.copy] §31 and §32 say: in a return statement in a function with ... . Am I right or wrong? 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 N-th type from a tuple?

I want to make a template where I can input an index and it will give me the type at that index. I know I can ... ). How can I do this? 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++ - Are multiple-inherited constructors called multiple times?

Are multiple-inherited constructors called multiple times? And in what order are constructors called? Does this ... DerivedBaseTwo() first? 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 config cmake for strip file

when I use cmake in Release mode I have the following binary: 64-bit LSB executable, x86-64, version 1 ( ... Release mode not strip my binary? 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 does tree vectorization make this sorting algorithm 2x slower?

The sorting algorithm of this question becomes twice faster(!) if -fprofile-arcs is enabled in gcc (4.7.2) ... code with the cmov instruction. 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 end() be a costly operation for stl containers

On https://doc-snapshots.qt.io/qtcreator-extending/coding-style.html it is recommended to write for loops like the ... call of end is mandatory. 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 valid to nest a critical section?

For example, would this be valid? CRITICAL_SECTION cs; ::InitializeCriticalSection( &cs ); ::EnterCriticalSection( ... 's accessor 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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