Recent questions tagged C++

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c++ - Find pair by key within a vector of pairs

I want to call the find function on a vector of pairs. At the time the find function is called I only ... better ways of implementing the logic. 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++ - Pass Parameter to Base Class Constructor while creating Derived class Object

Consider two classes A and B class A { public: A(int); ~A(); }; class B : public A { public: ... show some code to demonstrate this concept. 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 find the source of some macros

There are many places for defining a macro.When the macro is defined in our own project by us,the are easy to ... ,to find the source of them! 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++ - Disconnecting lambda functions in Qt5

Is it possible to disconnect a lambda function? And if "yes", how? According to https://qt-project.org/wiki/ ... , like sock->readAll(); } 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++ - Print template typename at compile time

When creating a template function in C++ is there a simple way to have the typename of the template ... be useful information to have. 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++ - Fullscreen widget

How can I make my widget fullscreen? I've tried something like this: void MainWindow::SetFullScreen() { // Make ... Any another ideas? OS: Linux 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++ - Function that accepts both lvalue and rvalue arguments

Is there a way to write a function in C++ that accepts both lvalue and rvalue arguments, without making it ... there something better I can do? 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++ - gdb: show typeinfo of some data

Basically, I want to get typeid(*this).name(), i.e. the real type of this. I want to get this in GDB ... included it there in the source file). 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 std::memcpy between different trivially copyable types undefined behavior?

I've been using std::memcpy to circumvent strict aliasing for a long time. For example, inspecting a float, like ... question will be the same. 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 use QVector(Qt) instead of std::vector

I'm very new to C++ and Qt, but I'm very good at C#/Java. The point is I like cross-platform, but I' ... ? A link would be nice, 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++ - Why is the construction of std::optional<int> more expensive than a std::pair<int, bool>?

Consider these two approaches that can represent an "optional int": using std_optional_int = std::optional<int>; using ... b[rip], 42 ret 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++ - PDF specifications for coders: Adobe or ISO?

I want to code an application that can read and decode a pdf document; now where I'm supposed to get the ... to start with this file format ? 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++ - Does C++11, 14, 17 or 20 introduce a standard constant for pi?

There is a rather silly problem with the number pi in C and C++. As far as I know M_PI defined in ... standard math functions work without pi? 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++ - Understand Op Registration and Kernel Linking in TensorFlow

I am fairly new to TensorFlow and right now looking into the custom op development. I have already read the ... for ops registration. 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 i can simulate a double mouse click on window ( i khow handle) on x, y coordinate, using SendInput?

How i can simulate a double mouse click on window ( i know handle of this window) on x, y coordinate, using SendInput? 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 style a Qt Widget not its children with stylesheets?

I have a: class Box : public QWidget and it has this->setLayout(new QGridLayout(this)); I tried doing: this ... Box widget, not its children? 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++ - List Iterator Remove()

I have a list iterator that goes through a list and removes all the even numbers. I can use the list iterator ... it will print properly } } } 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++ - STL Priority Queue on custom class

I'm having a lot of trouble getting my priority queue to recognize which parameter it should sort by. I've ... I missing and/or doing 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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c++ - When should you use direct initialization and when copy initialization?

Is it simply preference or are there specific instances where one is necessary over another? I'm refering to the ... e; // copy initialization 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 reduce redundant code when adding new c++0x rvalue reference operator overloads

I am adding new operator overloads to take advantage of c++0x rvalue references, and I feel like I'm producing ... t seem to think of anything. 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 get the size of a multi-dimensional cv::Mat? (Mat, or MatND)

I am creating a multi-dimensional MAT object, and would like to get the size of the object - e.g., const ... any methods in Mat::Mat or MatND 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 there no std::allocate_unique function in C++14?

Why does shared_ptr have allocate_shared while unique_ptr does not have allocate_unique? I would like to make a ... like an obvious idiom. 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 is a formal parameter?

When compiling in C++ I often end up with error messages dealing with "formal parameters", such as error ... in some abstract language calculus? 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++ - correct idiom for std::string constants?

I have a map that represents a DB object. I want to get 'well known' values from it std::map<std:: ... not simple const idiom for std:string 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 template polymorphism be used in place of OO polymorphism?

I am trying to get my head around applying template programming (and at some future point, template metaprogramming) ... what TMP really is. 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++ - opencv read jpeg image from buffer

I have an unsigned char* buffer containing data of a jpeg image. I would like to display that image using ... other suggestions? (Using Linux) 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++ - Write to memory buffer instead of file with libjpeg?

I have found this function which uses libjpeg to write to a file: int write_jpeg_file( char *filename ) { struct ... also difficult to come by. 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 run clang from command line on Windows?

At the Going Native conference last week, Chandler Carruth announced the existence of prebuilt binaries for running ... to such a walkthrough? See Question&Answers more detail:os...

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

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