Recent questions tagged C++

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c++ - Is it dangerous to use placement new on an old object without explicitly calling the destructor first?

I would like to recycle memory for an object rather than deallocating and reconstructing it. Is the following ... a more complex environment. 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++ - Weird result after assigning 2^31 to a signed and unsigned 32-bit integer variable

As the question title reads, assigning 2^31 to a signed and unsigned 32-bit integer variable gives an unexpected ... linux mint (if that helps) 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++ - Problem with functions accepting inner classes of template classes

I have a problem with inner classes in class templates. I have a template class (say: Matrix<T>), and a ... lot in advance for anything helpful! 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++ - failing to compile a project, missing io.h file

I fail to compile a C++ project for mobile device with Windows Mobile (Windows CE-based) operating system and ... me in the right direction? 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++ - Design of std::ifstream class

Those of us who have seen the beauty of STL try to use it as much as possible, and also encourage ... _Elem,class _Traits> class basic_ifstream; 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 do I implement a CString hash function for use with std::unordered_map?

I want to declare : std::unordered_map<CString, CString> m_mapMyMap; But when I build I got an error telling ... a hash function for CString? 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++ - Reproducibility of floating point operation result

Is it possible for an floating-point arithmetic operation to yield different results on different CPUs? By ... from different compilations. 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 store a leading zero in an int?

I have a programming assignment where I need to encrypt a 4 digit int, input by user. I have split the ... just print it within the function. 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++ - Openssl SSL_CTX_new(SSLv3_method()) returns NULL

Linux version from cat /proc/version Linux version 3.6.11-4.fc16.i686 (mockbuild@bkernel02) (gcc version 4.6 ... certs misc openssl.cnf private 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++ - Static members class vs. normal c-like interface

Hey there. After reading here about the Service Locator pattern, it got me thinking wether a class with only static ... Thanks for any help. :) 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++ - Construct std::function with a constructor based on template

Is it possible to construct a std::function with the constructor of a type defined by a template argument? For example: ... 't work //... } 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++ - Expose a vector as a memoryview using SWIG

I have a header file like: #include <vector> inline std::vector<uint8_t>& vec() { static std::vector< ... <uint8_t> as a Python memoryview? 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++ - Passing a vector by reference and changing its values in a range-based for loop?

I'm trying to change the values of a vector by doing something similar to the following function: vector<int> ... a range-based for loop? See Question&Answers more detail:os...

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

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225 views

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c++ - Compiling a MFC app from Visual Studio 2010 to 2012 RC results in LNK2038

My project is compiling and running OK in debug and release modes in VS 2010. Today I tried to compile it with ... how I can solve this problem. 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++ - Hide label text for Qt tabs without setting text to empty string

I need a QTabWidget with icons only: How can I hide the label text of a tab in Qt? I cannot set the text to ... handle (agree with PS on 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++ - Evaluation of C expression

int main() { int i = -3, j = 2, k = 0, m; m = ++i || ++j && ++k; printf("%d %d %d ... . What is going on here? What are the intermediate steps? 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 can't I use variable of parent class that is template class?

a.h template <typename T> class A { public: int a; } b.h template <typename T> class B : public A<T ... some method? (I fixed some mistakes) See Question&Answers more detail:os...

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

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306 views

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c++ - Invalid covariant type with CRTP clonable class

I'm trying to implement a Clonable class with the CRTP. However, I need to have abstract class that have a pure virtual ... A, Clonable<B> { }; 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++ - Bug in std::regex?

Here is code : #include <string> #include <regex> #include <iostream> int main() { std::string pattern("[ ... org/bugzilla/show_bug.cgi?id=63497 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 the compiler allowed leeway in what it considers undefined behavior in a constant expression?

We know that operations that would cause undefined behavior are not core constant expressions(section 5.19 paragraph ... and hence my question. 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++ - Boost spirit poor performance with Alternative parser

I already asked question about this issue. But since there were no answers i'm asking again now with full compilable ... "Syntax is 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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385 views

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c++ - Is using const_cast for read-only access to a const object allowed?

In C++ I have a function that only requires read-only access to an array but is mistakenly declared as ... or when accessing the array? 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 use/install custom Directshow filter

I have custom compiled directshow filter - filter.DLL - but how to use, or install this filter in system? 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 with OpenCV ROI

I am trying to make a program that will identify a pattern by sliding a ROI over an image and comparing the ... is simple thank you 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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308 views

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c++ - Array of polymorphic base class objects initialized with child class objects

Sorry for the complicated title. I have something like this: class Base { public: int SomeMember; Base() : ... Is this at all possible? See Question&Answers more detail:os...

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

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366 views

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c++ - Creating a sub-tuple starting from a std::tuple<some_types...>

Let us suppose that a std::tuple<some_types...> is given. I would like to create a new std::tuple whose ... to discard some of them? 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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196 views

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c++ - NPAPI support in Firefox and Chrome actually dropped?

Recently I've found out that Chrome and Firefox are dropping NPAPI plugins support by January 2013. Anyway, reading ... this remain this way? 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 don't std::algorithms work directly on containers as well?

Possible Duplicate: STL algorithms taking the whole container rather than .begin(), end() as arg? I have been looking ... I don't know about? See Question&Answers more detail:os...

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

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