Recent questions tagged C++

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c++ - How to convert a time into epoch time?

Say I have a specific instant in time where I know the hour, minute, day, second, month, year, etc; how ... don't suggest a Boost solution. 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 there an easy way to tell if a class/struct has no data members?

Hallo, is there some easy way in C++ to tell (in compile-time) if a class/struct has no data members? E.g ... I would like to switch on 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++ - Are the character digits ['0'..'9'] required to have contiguous numeric values?

Must a C++ implementation set the chars '0'-'9' to have contiguous numeric values, i.e. so that: '0' -> 0 ... the vector form of ctype<>::is. 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 simulate printf's %p format when using std::cout?

unsigned char *teta = ....; ... printf("data at %p ", teta); // prints 0xXXXXXXXX How can I print variable ... ? (no sprintf's, please ;)) 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 does the stl's multimap insert respect orderings?

I have some data which come with a integer index. I am continuous generating new data which needs to added to the ... it seems like it doesn't. 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++ - C++11 Change `auto` Lambda to a different Lambda?

Say I have the following variable containing a lambda: auto a = [] { return true; }; And I want a ... knowledge about auto or lambdas. Thanks. 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 std::array<T, S> guaranteed to be POD if T is POD?

I'm currently writing a C++ memory editing library and for the read/write APIs I use type traits ( ... Hades-Memory/Hades-Memory/MemoryMgr.h#86 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 failbit set when eof is found on read?

I've read that <fstream> predates <exception>. Ignoring the fact that exceptions on fstream aren't very ... the stream before doing so? 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 are std::atomic objects not copyable?

It seems that std::atomic types are not copy constructible or copy assignable. Why? Is there a technical reason why ... some sort of bad 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++ - Error redeclaring a for loop variable within the loop

Consider this snippet of a C program: for(int i = 0; i < 5; i++) { int i = 10; // <- Note the local ... < 5; i++) ^ Why is this happening? 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 tell g++ compiler where to search for include files?

In a "working directory" I have a lot of *.cpp and *.h files that #include each other and files from ... command line (using g++). 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 the return type of boost::bind?

I want to save the "binder" of a function to a variable, to use it repetitively in the following code ... like to have my operator overloading. 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++ - Sort filenames naturally with Qt

I am reading a directories content using QDir::entryList(). The filenames within are structured like this: ... place to implement it? 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 does the template-id in "A<0>=0" not compile without space because of the greater-or-equal-than operator ">="?

template <int> using A = int; void f(A<0>=0); // Attempting to declare a function f taking int, // ... something or is this a compiler bug? 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++ - std::function to member function

#include <functional> struct A { int func(int x, int y) { return x+y; } }; int main() { typedef std ... error? I am using visual studio 2010 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 aggregate initialization

The section "Array Initialization" in Chapter 4, page 231 of "Thinking in Java, 2nd Edition" has this to say ... 't convince me of anything. 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++ - Cannot load any image with CImg

Any time I try to load an image I get an error saying CImg<unsigned char>::load(): Failed to recognize ... ask specifically. What's gone 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++ - Creating QT Application as GUI for existing console-based application on windows

i'm trying to set up a GUI with Qt for an existing application which is meant to be run in the windows ... on windows. Thanks for your 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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c++ - IBM Single Precision Floating Point data conversion to intended value

I need to read values from a binary file. The data format is IBM single Precision Floating Point (4-byte ... buffer into floating point values? 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++ - Stop QTableView from scrolling as data is added above current position

I have a simple QTableView with a QSortFilterProxyModel and a source model of a custom TableModel subclass that inherits ... say a selected row? 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 do I load a C DLL from the SXS in Python?

This is typically done by specifying the DLL dependency in a manifest file that resides with the executable. ... way to accomplish 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++ - Returning reference to a local variable

Why can this code run successfully in Code::block. The IDB just reports warning: "reference to local variable tmp' ... )<<endl; return 0; } 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++ - VC2013: function from bind not compiling

Here is a short sample: class A {}; class S {}; class B { public: typedef std::function <bool (A& retVal)> ... _Ret,A &>::_Do_alloc<_Myimpl,std::_Bind<true,_Ret,std::_Pmf_wrap<boo...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Using SDL_image in Visual studio 2010, with error "application was unable to start correctly 0xc000007b"

I'm trying to do the SDL tutorial here http://lazyfoo.net/SDL_tutorials/lesson03/windows/msvsnet2010e/index. ... visual stdio 2010 professional See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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312 views

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c++ - How to Create a HTTP MJPEG Streaming Server With QTcp-Server Sockets?

I want to create a Http Server to send an MJPEG Stream. I'm Already able to send an Image but no Live-Stream. ... (500); } m_Client->close(); See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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148 views

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c++ - how to use gpu::Stream in OpenCV?

OpenCV has gpu::Stream class that encapsulates a queue of asynchronous calls. Some functions have overloads with the ... of gpu::Stream. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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194 views

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c++ - Data structure padding

What is data structure padding in c++ and how do i check the number of bytes padded bytes? class a { public: int x; int y; int z; }; See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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550 views

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c++ - Vector.erase(Iterator) causes bad memory access

I am trying to do a Z-Index reordering of videoObjects stored in a vector. The plan is to identify the ... I'm taking the wrong turn. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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