Recent questions tagged C++

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c++ - length of va_list when using variable list arguments?

Is there any way to compute length of va_list? All examples I saw the number of variable parameters is given explicitly. 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++ - sign changes when going from int to float and back

Consider the following code, which is an SSCCE of my actual problem: #include <iostream> int roundtrip(int x ... both outputs perfectly valid? 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++ cli - How to use Nullable types in c++/cli?

I have the following code, which I thought would work: property Nullable<double> Angle { Nullable<double> get ... even support nullable types? 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 __int128_t faster than long long on x86-64 GCC?

This is my test code: #include <chrono> #include <iostream> #include <cstdlib> using namespace std; using ll = ... type. How does this happen? 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 class { int i; }; is not fully standard-conformant?

This is a follow-up question. In the previous question, @JohannesSchaub-litb said that the following code is ... quoting the Standard)? 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++ - Instantiation of template member function

In Class.h: class Class { public: template <typename T> void function(T value); }; In Class.cpp: template< ... a non-template class ? 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++ - How to intentionally delete a boost::shared_ptr?

I have many boost::shared_ptr<MyClass> objects, and at some point I intentionally want to delete some of them to ... old value and delete 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++ - Visual Studio No Symbols have been loaded for this document

I am having some trouble debugging a visual studio 2008 C++ project. When I start running it in debug, the ... this or how to 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++ - error: anachronistic old-style base class initializer

The following code produces the subsequent compilation error on all versions of GCC that I've tried, in C++98 ... why their program was broken. 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++ - Make GNU make use a different compiler

How can I make GNU Make use a different compiler without manually editing the makefile? 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 does cout << " "[a==N]; do?

In the following example: cout<<" "[a==N]; I have no clue about what the [] option does in cout, but it does ... the value of a is equal to N. 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++ - Equivalent of %02d with std::stringstream?

I want to output an integer to a std::stringstream with the equivalent format of printf's %02d. Is there an easier ... flags("%02d") << value; 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 would you use the keyword const if you already know variable should be constant?

Many of the books that I am reading use keyword const when the value of a variable should not be modified. ... someone clarify this for me? 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++ - haar training OpenCV assertion failed

I am trying to train a haar-like classifier for pedestrians in OpenCV using 3340 positive images and 1224 negative ... what is causing 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++ - Define array, then change its size

I come from a java background and there's something I could do in Java that I need to do in C++, but I'm not sure ... ; How do I do this in 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++ - Any Tutorials for Win32 SDK Programming?

What are some good websites for Win32 SDK programming tutorials? See Question&Answers more detail:os...

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

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230 views

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c++ - Using Boost in android ndk with windows

I am trying to use boost library with Android ndk in Eclipse with Windows. I tried to follow this tutorial I ... help me with this please? 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 Qt with DirectX?

What exactly are my options? I have programs I need to write in OpenGL and DirectX, and I'd like to use Qt ... working? Has it been done before? 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++ - Calculating e^x without using any functions

We are supposed to calculate e^x using this kind of formula: e^x = 1 + (x ^ 1 / 1!) + (x ^ 2 ... 21840746155e+307 The program is written in 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++ - How can I use the skipper ascii::space WITHOUT skipping eol?

I have to use boost::spirit for parsing, and I want use phrase_parse function : qi::phrase_parse(str.begin(), ... ::space WITHOUT skipping eol ? See Question&Answers more detail:os...

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

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151 views

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c++ - Using template instead of switch

I want to perform a set of tests in my code that are similar but change only depending on a ... reduce the maintenance overhead. 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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507 views

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c++ - How to use libssh in VS10

How can I implement libssh as a library my compiler will recognize? I'm using Visual Studio 2010 C++, and I ... is libssh not libssh2. 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++ - Android std and stl support

I am playing with android ndk. I am using Window Vista with cygwin (latest version). I compiled and launched the ... file in an android ndk app? See Question&Answers more detail:os...

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

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288 views

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c++ - OpenMP - Nested for-loop becomes faster when having parallel before outer loop. Why?

I'm currently implementing an dynamic programming algorithm for solving knapsack problems. Therefore my code has two ... according to 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++ - The difference between cin.ignore and cin.sync

What is the difference between cin.ignore and cin.sync ? 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 make Visual Studio save all files as UTF-8 without signature on Project or Solution level?

I am trying to configure a VS c++ project in a way that it can be compiled by gcc in Linux. It ... to change their Visual Studio settings. See Question&Answers more detail:os...

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

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334 views

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c++ - How to programmatically disable the auto-focus of a webcam?

I am trying to do computer vision using a webcam (the model is Hercules Dualpix). I know it is not the ... the camera with the auto-focus. See Question&Answers more detail:os...

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

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236 views

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c++ - How do I get back c++0x/c++11 support for Mac OS X 10.6 deployment using Xcode 4.6.2 thru 7.1.1

I heavily use the c++0x/c++11 features in my project, particularly code blocks and shared pointers. When I ... is required for those OSes). See Question&Answers more detail:os...

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

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