Recent questions tagged C++

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c++ - Why are consecutive int data type variables located at 12 bytes offset in visual studio?

To clarify the question, please observe the c/c++ code fragment: int a = 10, b = 20, c = 30, ... ! Can anyone please explain this behavior? 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++ - Error: symbol(s) not found for architecture x86_64, collect2: ld returned 1 exit status

I have been struggling for a while with an issue on Qt. Here is my code: hexbutton.h: #ifndef HEXBUTTON_H #define ... . Thank you for your help! 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++ - bitwise operations on vector<bool>

what's the best way to perform bitwise operations on vector<bool>? as i understand, vector<bool> is a ... access the actual values. 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 could cause a dynamic_cast to crash?

I have a piece of code looking like this : TAxis *axis = 0; if (dynamic_cast<MonitorObjectH1C*>(obj)) axis = ... it should just return NULL no ? 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 I treat a specific warning as an error?

The following is a simplified version of a pattern I sometimes see in my students' code: bool foobar(int a, ... as errors. Is that possible? 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 create a std::function with a custom allocator?

To save some code lets say I have a custom allocator named MyAlloc which I have successfully used with a ... std::function have been deprecated 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++ - timegm cross platform

I'm using Visual Studio c++ Compiler ( 2010 ), but the library has different implementation of ANSI C and POSIX ... t->tm_sec; return result; } 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++ - Initialize a reference - warning C4355: 'this' : used in base member initializer list

class A; class B { public: B(A& a) : a(a) {} private: A& a; }; /* Method 1 */ /* warning ... just that I am not comfortable with the warning. 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++ - Range-based for statement definition redundancy

Looking at n3092, in §6.5.4 we find the equivalency for a range-based for loop. It then goes on to say what ... [N]); Returns: array + N. 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 purpose of __in __out __in_opt __allowed(), how do they work? Should I use similar constructs in my own code?

Some of these Preprocessor definitions are in the WinMain function and other windows library functions. What is their ... is supposed to work. 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++ - Check if type is hashable

I would like to make a type trait for checking if a particular type is hashable using the default instantiations of ... a SFINAE non-error)? 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++ - Calling base class definition of virtual member function with function pointer

I want to call the base class implementation of a virtual function using a member function pointer. class Base ... that would also help. 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++ - C++0x const RValue reference as function parameter

I am trying to understand why someone would write a function that takes a const rvalue reference. In the code example ... ()); return 0; } 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 not overload operator+=() for std::vector?

I've started learning C++, so I don't know in my lack of knowledge/experience why something so seemingly simple ... who are proficient in 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++ - Delete objects of incomplete type

This one made me think: class X; void foo(X* p) { delete p; } How can we possibly delete p if we do ... g++ does? Or is it undefined behavior? 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++ - Vector converted all negative values to zero

I made a vector of constant size to store negative values, and then printing the values all I got was zeroes. I ... / All I got was zeroes } 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++ - Is delete allowed to modify its parameter?

In an answer, https://stackoverflow.com/a/704568/8157187, there is a quote from Stroustrup: C++ explicitly allows an ... so 6.7 doesn't apply. 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++ - Move list element to the end in STL

I have already the list pointer of CDrawObject* std::list<CDrawObject*> elements; How I can move some element to the ... . How i can do 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++ - find out the type of auto

I am playing with generic lambda in C++1y and I often confused by don't know what is the type of auto variable/ ... and I am using Xcode 5.1.1 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++ - Multiple dispatch solution with full maintainability

Can someone think of a good way to implement multiple dispatch with something like the Object::foo overloads below? class A { public: ... ::cout << "Object::foo C,B "; return 3.14...

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

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c++ - Copy constructor not called?

As far as I know you call the copy constructor in the following cases: 1 When instantiating one object and initializing ... < endl; return 0; } 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++ - Dynamic Memory Allocation in MPI

I am new to MPI. I wrote a simple code to display a matrix using multiple process. Say if I have a matrix ... *sizeof(int)); it works perfectly. 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 if condition in intrinsics

I want to compare two floating point variables using intrinsics. If the comparison is true, do something else do ... this using SSE2 or AVX? 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++ - OpenSSL's rsautl cannot load public key created with PEM_write_RSAPublicKey

I've generated a public key using openssl BIGNUM* e = BN_new(); BN_set_word(e, 17); RSA* rsa = RSA_new(); ... load Public Key What am I missing? 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++ - DLL call with __stdcall & GetProcAddress() in VS2013

I'm trying to call a function from my own DLL, but depending on the calling convention in the DLL project ... compiler is "Visual Studio 2013". See Question&Answers more detail:os...

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

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369 views

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c++ - Detect if WM_MOUSEMOVE is caused by touch/pen

I am experimenting with WM_TOUCH and want to detect if mouse events are synthesized from touch/pen events or due to ... , touch and pen inputs? 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++ - Could not compile a "hello world" cpp in my OSX

I wrote a hello world program on my mac, but when I compiled it, the compiler output an error: Undefined symbols ... "hello world"; return 0; } See Question&Answers more detail:os...

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

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278 views

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c++ - Constructor to specify zero-initialization of all builtin members?

Is there a simpler way for a class's constructor to specify that all members of built-in type should be zero ... stops getting 0 by chance. See Question&Answers more detail:os...

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

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