Recent questions tagged C++

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c++ - c++11 std::async doesn't work in mingw

Running this code from Herb Sutter's presentation. This works fine in linux under gcc 4.6.3. I'm thinking that ... gcc version 4.7.0 (GCC) 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++ - Size of Primitive data types

On what exactly does the size of a primitive data type like int depend on? Compiler Processor Development ... don't look irrelevant. 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++ - Protected data in parent class not available in child class?

I am confused: I thought protected data was read/writable by the children of a given class in C++. The below ... A' What am I doing wrong? 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++ - Inheriting and overriding functions of a std::string?

Since std::string is actually a typedef of a templated class, how can I override it? I want to make a ... correct length, among other things. 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 is this SIMD multiplication not faster than non-SIMD multiplication?

Let's assume that we have a function that multiplies two arrays of 1000000 doubles each. In C/C++ the function looks ... time 1.09, 22.08 GB/s 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++ - When does a std::vector reallocate its memory array?

I can't find anything that gives a definitive answer. I was just curious if a std::vector reallocate its ... that this is expected 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++ - Access to method pointer to protected method?

This code: class B { protected: void Foo(){} } class D : public B { public: void Baz() { Foo(); } ... things to work the way I was expecting). 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 using an union in place of a cast well defined?

I had a discussion this morning with a colleague regarding the correctness of a "coding trick" to detect endianness. ... ? Who is right here ? 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 make sure that std::random_shuffle always produces a different result?

Is there some function, similar to srand(), that I need to call to make sure that std::random_shuffle() always ... can I make sure of that? 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++ - Does it make sense for unary operators to be associative?

The C++ operator precedence table from http://en.cppreference.com/w/cpp/language/operator_precedence (I know ... operators to be associative? 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 are the differences between std::variant and boost::variant?

In an answer to this SO question: What is the equivalent of boost::variant in the C++ standard library? it is ... :variant in pre-C++17 code) 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++ - Conditionally replace regex matches in string

I am trying to replace certain patterns in a string with different replacement patters. Example: string test = ... replaced with empty string. 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++ - Specialized template function with deleted "general" case fails to compile with g++ <=4.8.0 and clang++

Compiling a project with an older version of g++ (4.8.0, MinGW) I found that this code fails to compile: template ... still doesn't work in 3.7) 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++ - Advantage of using trailing return type in C++11 functions

What is the advantage of specifying a trailing return type in C++11, as opposed to a normal return type? Look at foo1 ... ) { foo1(); foo2(); } 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++ - Will I be able to declare a constexpr lambda inside a template parameter?

I know it's like opening the Pandora box but it doesn't stop bothering me. Consider a simple example: #include < ... or will C++17 allow this? 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++ - Unit test that a class is non copyable, and other compile-time properties

Is there a way to test compile-time errors, but without actually generating the error? For example, if I ... using boost::noncopyable and such. 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 can't std::function bind to C-style variadic functions?

For example, this fails to compile: std::function<decltype(printf)> my_printf(printf); With gcc, the error ... the technical reason for this? 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 delete on NULL pointers - C++03 vs C++11

In the C++03 Standard, I see: 5.3.5 Delete 2 If the operand has a class type, the operand is ... to almost nothing between 2003 and 2011? 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++ - Accessing parent's protected variables

I couldn't think of a better wording for the title, so it is a little misleading, however, I am not talking ... I was hoping for a cleaner way. 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 an explicit constructor with a braced-init list: ambiguous or not?

Consider the following: struct A { A(int, int) { } }; struct B { B(A ) { } // (1) ... so such implicit construction should not be allowed. 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 adding code to a loop make it faster?

I have a simple function with an inner loop - it scales the input value, looks up an output value in a ... inc edx dec eax jne SHORT $L4457 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 "operator<<" called?

I know the names of most of the operators but not sure what operator<< and operator>> are called. i.e. ... -than operator and so forth... 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 SFINAE class template specialisations using void_t

Are multiple class template specialisations valid, when each is distinct only between patterns involving template parameters ... :true_type {}; 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++ - OpenGL: glGetError() returns invalid enum after call to glewInit()

I use GLEW and freeglut. For some reason, after a call to glewInit(), glGetError() returns error code 1280, even ... } What I am doing wrong? 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++ - fatal error C1083: Cannot open include file: 'xyz.h': No such file or directory?

I am using visual studio 2005 to create a project. And I have folder structure in project as: a folder called ... . how to rectify this problem. 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++ - Should std::unique_ptr<void> be permitted

This is a very simple question. Consider the following code: #include <iostream> #include <memory> typedef std:: ... other errors were fixed). 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++ - Free function versus member function

What is the advantage of having a free function (in anonymous namespace and accessible only in a single source ... be member functions or free? 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++ - Expand macro inside string literal

What I'm trying to do is to #define a macro: #define a(2) and later use it inside a string literal: ... didn't succeed, can anybody 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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