Recent questions tagged C++

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c++ - Executing MSYS from cmd.exe with arguments

I am trying to learn the wxWidgets library, using MinGW and msys to compile the code. So far so good, but I ... an easier way, please show 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++ - Automatically separate class definitions from declarations?

I am using a library that consists almost entirely of templated classes and functions in header files, like this: // ... help me in this case? 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 create qt label hover effect?

I must use hover event on Qt label, but I can't found no information about that. I try use something like ui- ... . I must change text on hover. 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++ - Recording Video from USB Cam with Qt5

I am trying to record a video acquired from a webcam connect to the usb device. I am workin with Qt5.1. ... But the video is actually recorded. 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++ - Topological sorting using std::sort

Note: While writing this question, I think I already found the answer. Feel free to ammend or append it ... not backed up by argumentation. 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 you reinterpret_cast between types which have the same representation?

Suppose we have two types, that have the same representation (the same member variables and base classes, in the ... C++ language allows 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++ - Is it possible to debug into a DLL with only a PDB and no source code?

I'm trying to debug an exe that calls a dll, in Visual Studio. I made sure I had the corresponding pdb in ... lib) built using the /Z7 option? 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++ - Initializing members with members

This is a problem I come across often. The following examples illustrates it: struct A { int m_SomeNumber; } ... suggestions how to handle 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++ - Are redundant include guards necessary?

Are 'redundant include guards' necessary in Codegear RAD Studio 2009? Is the compiler smart enough to deal with this on ... e.g. use_foo.cpp. ? 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++ - Testing for a maximum unsigned value

Is this the correct way to test for a maximum unsigned value in C and C++ code: if(foo == -1) { // at ... int, an unsigned short, and so 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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c++ - How to Link a third Party Library (LibUSB) in CMake

I am attempting to use LibUSB in a project. However whenever I attempt to use basic libUSB functions I get ... / add_executable(main main.cpp) 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++ - casting between sockaddr and sockaddr_in

I came across a socket programming tutorial in which it is quoted "a pointer to a struct sockaddr_in can be cast ... the size remains 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++ - How does Float round when converting it into integer

If I have (float)value = 10.50 and do int new_value = (int)value what rules will round number? See Question&Answers more detail:os...

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

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661 views

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c++ - Setting program icon without resources using the WIN32 API

I am working with the express version of Visual Studio. Therefore, using functions calls to MAKEINTRESOURCE are ... WITHOUT using a resource? See Question&Answers more detail:os...

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

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902 views

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c++ - Isn't 'virtual' keyword redundant when 'override' or 'final' specifiers are used?

Let's say I have the following base class: class Base { public: virtual void f() {}; }; If I want ... . Which one approach is more appropriate? 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++ - Sun Studio linking gcc libs: exceptions do not work

I need to build an application with Sun Studio. This application uses a shared library which can only be build ... ( clayer SHARED clayer.cpp ) See Question&Answers more detail:os...

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

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703 views

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c++ - Computing length of array

I have a C++ array declared as mentioned below: CString carray[] = { "A", "B", "C", "D", "E ... sizeof(carray)/sizeof(CString); Is this correct? 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++ - Plugging custom transport into gRPC

Let‘s assume we develop a custom low level transport for gRPC. How can we “plug it” into the gRPC c++ API so that we can use it for a Channel? See Question&Answers more detail:os...

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

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971 views

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c++ - C++11 thread_local in gcc - alternatives

As I can see at: http://gcc.gnu.org/projects/cxx0x.html thread_local keyword is unfortunately unsupported in gcc ... want to use boost library. 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++ - Convert from MinGW .a to VC++ .lib

I have an old library (in C++) that I'm only able to build on MinGW+MSYS32 on Windows. From that I can ... .a file to VC++ library 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++ - Get text width in MFC

I'm wanting to dynamically resize a CButton to the width of the text within it. Is there either a built-in ... I can use CWnd::SetWindowPos)? See Question&Answers more detail:os...

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

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700 views

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c++ - Why use new and delete at all?

I'm new to C++ and I'm wondering why I should even bother using new and delete? It can cause ... hard to google that specific 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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665 views

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c++ - std::string in struct - Copy/assignment issues?

Suppose I have a struct containing a std::string, like this: struct userdata{ int uid; std::string username ... explicitly create a new 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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602 views

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c++ - Access to private nested class returned from member function

Please help me understand why it is possible for a class member function to return a private nested class object, and why it ... x3.f(); // 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++ - Why do both the notify and wait function of a std::condition_variable need a locked mutex

On my neverending quest to understand std::contion_variables I've run into the following. On this page it says the ... . So please enlighten 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++ - Monitor battery charge with Win32 API

I'm trying to write a small app that monitors how much power is left in a notebook battery and I'd like to ... I could use to accomplish 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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582 views

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c++ - Why does INVOKE facility in the C++11 standard refer to data members?

$ 20.8.2 of the standard describes the INVOKE facility that is mostly used to describe how callables are called with ... and *f() was intended? 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 no push/pop in front of vector?

In C++, STL, we have template class <vector>. We know that it supports O(1) random access, and tail ... /pop_front for <vector>. Any thoughts? See Question&Answers more detail:os...

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

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