Recent questions tagged C++

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If I defined a class: class Blah {}; How can I: std::string const className = /* What do I need to do ... ::className() to get the class name. 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 using NULL references OK?

I came across this code: void f(const std::string &s); And then a call: f( *((std::string*)NULL) ) ... what do you think of this construction? 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 storing unrelated data in the least-significant-bit of a pointer work reliably?

Let me just say up front that what I'm aware that what I'm about to propose is a mortal sin, ... supercomputers or anything exotic like that) 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 specialize a class template with an alias template?

Here's a simple example: class bar {}; template <typename> class foo {}; template <> using foo<int> = bar; Is this allowed? 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++ - Setprecision is Confusing

I just want to ask about setprecision because I'm a bit confused. here's the code: #include <iostream> ... wrong? please enlighten me. 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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295 views

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c++ - Policy with catching std::bad_alloc

So I use Qt a lot with my development and love it. The usual design pattern with Qt objects is to ... involving other scenarios as well. 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++ - Extract high resolution icon or thumbnail for file

I'm trying to get a high resolution icon or thumbnail in Windows given a full path to that file. Doesn't ... anything better than 32x32 ... 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 do we need to set rvalue reference to null in move constructor?

//code from https://skillsmatter.com/skillscasts/2188-move-semanticsperfect-forwarding-and-rvalue-references class Widget { ... .pds = nullptr; 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++ - A way to load DLL from central repository

We have lot of products and there are some common DLLs across each product's application. Right now we copy ... our private directory ] -Kartlee 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 can I simulate a button click given the handle to the button's window?

I want to simulate a click on a button located in a dialog box. I have the handle to that window. This is an ... as it doesn't suit my needs. See Question&Answers more detail:os...

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

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254 views

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c++ - What does the "::" mean in "::tolower"?

I've seen code like this: std::string str = "wHatEver"; std::transform(str.begin(), str.end(), str.begin( ... not works, but ::tolower works OK 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++ - shared_ptr and cyclic references

I was trying with the cyclic references for boost::shared_ptr, and devised following sample: class A{ // ... required? Thanks in advance. 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++ - BitBlt performance with Aero enabled

I'd like to get more performance out of BitBlt for capturing the screen. When Aero remains enabled, capturing ... screen when Aero is disabled. See Question&Answers more detail:os...

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

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186 views

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c++ - Using make to move .o files to a separate directory

I've tried numerous attempts to move my .o files to my obj folder, but no matter what I do, it simply just ... (INCLUDEPATH) -c main.cpp $(OBJ) 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 specify target mac os x version using qmake

I am trying to compile c++11 code on the Mac OS X using Qt Creator/qmake and I am getting the ... Any suggestions would be helpful. 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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260 views

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c++ - Access Base class variable from child class method

How can I access base class variable from a child method? I'm getting a segmentation fault. class Base { public: ... Child(); child->foo(); See Question&Answers more detail:os...

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

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266 views

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c++ - CreateProcess succeeds, but GetExitCodeProcess returns C0000142

I'm trying to start a user-mode process from a service using CreateProcessAsUser() API similar to this code. ... code 0xC0000142. Any idea 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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270 views

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c++ - Compile header-only template library into a shared library?

We are in the process of designing a new C++ library and decided to go with a template-based approach ... but also the partial specialisations.. See Question&Answers more detail:os...

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

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299 views

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c++ - Converting an Integer Array into a Number

Think I have an integer array like this: a[0]=60; a[1]=321; a[2]=5; now I want to convert the whole ... after running the code. How to do 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++ - Different template syntax for finding if argument is a class or not

While reading this question , I came across @Johannes's answer. template<typename> struct void_ { typedef void type; ... parameter in Line 2 ? See Question&Answers more detail:os...

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

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519 views

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c++ - How to generate 64 bit random numbers?

I'm implementing universal hashing and using the following universal hash function : h(k)=((A*k)mod 2^64) ... number returned by rand is int. See Question&Answers more detail:os...

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

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202 views

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c++ - Exception slicing - is this due to generated copy constructor?

I've just fixed a very subtle bug in our code, caused by slicing of an exception, and I now want to make ... confirmation of what was going on. See Question&Answers more detail:os...

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

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362 views

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c++ - Clang VS VC++:"error: declaration of 'T' shadows template parameter"

I was trying to compile the following code for the classic copy&swap idiom on my Mac with clang 3.3 template< ... This works under clang too. See Question&Answers more detail:os...

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

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174 views

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c++ - What is a char*?

So I've been watching lectures from a University about C++, and I'm learning a lot, but one thing I still ... but maybe I'm just dead 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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298 views

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c++ practical computational complexity of <cmath> SQRT()

What is the difference in CPU cycles (or, in essence, in 'speed') between x /= y; and #include <cmath> x = ... as a benchmark for x = sqrt(y) See Question&Answers more detail:os...

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

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399 views

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c++ - Synchronizing STD cout output multi-thread

Latelly I've been working with multi-thread coding, after a while writing I realized that if I used std::cout in ... . Thank you for your 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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174 views

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c++ - How to use/create boost::multi_index?

Can someone explain to me in detail how to create a multi index map using boost::multi_index? I saw many examples ... X and some are not unique. See Question&Answers more detail:os...

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

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335 views

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c++ - Translating a std::tuple into a template parameter pack

I have a typedef std::tuple<A, B> TupleType; and would like to use the list of classes for a "template". ... failed "; } return res; } See Question&Answers more detail:os...

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

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