Recent questions tagged C++

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I tried this, and some variations on it: template<class T> class Ptr { public: Ptr(T* ptr) : p(ptr) {} ~ ... with C++0x: http://ideone.com/lMlyB 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 dllexport a class derived from std::runtime_error?

I have set up a library providing an exception class derived from the standard exception: #include <stdexcept> #include ... be possible. So...? 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++ - reinterpret_cast, char*, and undefined behavior

What are the cases where reinterpret_casting a char* (or char[N]) is undefined behavior, and when is it defined behavior? ... C++11 to C++1z? 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 it allowed to call derived class' private virtual method via pointer of base class?

# include <iostream> using namespace std; class A { public: virtual void f() { cout << "A::f()" << ... works, but why is this code allowed? 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++ - Using nested vectors vs a flatten vector wrapper, strange behaviour

The problem For a long time I had the impression that using a nested std::vector<std::vector...> for ... all the memory contiguously allocated? 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's a fluent interface?

I recently came across this expression - but reading up on Wikipedia did not clarify it much for me - I still ... C++ interface for example)? 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 deleted constructors "accessible"?

A deleted answer on this question about a deleted move constructor quotes cppreference.com as saying that the ... about this either 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++ - How are u8-literals supposed to work?

Having trouble to understand the semantics of u8-literals, or rather, understanding the result on g++ 4.8.1 ... confused now than before... 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 there any std::chrono thread safety guarantee even with multicore context?

First, I'm assuming that calling any function of std::chrono is guaranteed to be thread-safe (no undefined ... always from the same core? 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++ - cannot convert parameter 1 from 'char *' to 'LPCWSTR'

Im trying to load a BMP file AUX_RGBImageRec *LoadBMP(char *Filename) // Loads A Bitmap Image { FILE *File=NULL; ... ' how could I correct 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++ - template overloading and SFINAE working only with functions but not classes

can someone explain why the compiler accepts only this code template<typename L, size_t offset, typename enable_if ... of the first. 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 multi-line macros have backslashes at the end of each line?

In a macro declaration like: #define WAIT_SPI2_TRANSMISSON_END() {while ((SPI2_SR & SPI_SR_TXCTR_MASK) != 0) { if( ... ) mean or do there? 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 can I skip the first iteration of range-based for loops?

I would like to do something like this: for (int p : colourPos[i+1]) How do I skip the first iteration of my ... I use .begin() and .end()? 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 there a difference between <winsock.h> and <winsock2.h>?

I'm including as it's required by the MySQL C library. The auto-complete in VS2010 is also showing a - any ... of one over the other? 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++ - Determine if angle lies between 2 other angles

I am trying to figure out whether a angle lies between 2 other angles. I have been trying to create a simple function ... )); } return -1; } 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 pass a C++11 random number generator to a function?

Do they all inherit from a base class? Do I have to use templates? (I am referring to these http://www.codeguru.com/cpp/ ... >(0, n)(gen); } }; 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++ - c++11 interprocess atomics and mutexes

I have a Linux program which spawns several processes (fork) and communicates through POSIX Shared Memory. I'd ... once across all processes? 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 identify failed casts using dynamic_cast operator?

Scott Meyer in his book Effective C++ says dynamic_cast is used to perform safe casts down or across an ... casting reference can be indicated. 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++ - Simplest way to count instances of an object

I would like to know the exact number of instances of certain objects allocated at certain point of execution. ... to count object instances? 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 do a reduction on an array with openmp?

Does OpenMP natively support reduction of a variable that represents an array? This would work something like the ... happen via binary tree. 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++ - Case expression not constant

I am getting a 'case expression not constant' error in a switch statement. However, the header provides a ... case? It seems unlikely. 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++ - I want to wait on both a file descriptor and a mutex, what's the recommended way to do this?

I would like to spawn off threads to perform certain tasks, and use a thread-safe queue to communicate ... blocking and not servicing requests. 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 does "symbol value" from nm command mean?

When you list the symbol table of a static library, like nm mylib.a, what does the 8 digit hex that ... having the symbol value of 00000000? 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++ - Selecting a row in QTreeView programmatically

I have a QTreeView with QFileSystemModel as model. The QTreeView has SelectionBehavior set to SelectRows. In my code I ... only way to do it? 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++ - Eclipse 3.7.0 Indigo with CDT shows many false compilation errors

I have updated my Ubuntu box to 11.10 and then Eclipse also have been updated to 3.7.0 Indigo with CDT 8.0 ... the code, it had no 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++ - how to force compilation of Boost to use -fPIC

The team on which I work produces a shared library for use in Python. This library is entirely C++ and ... the static libraries that it builds? 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 any difference between std::forward<T> and std::forward<decltype(t)>?

are these functions equivalent? template <class T> void foo(T && t) { bar(std::forward<T>(t)); } template <class T ... ::forward<U>(para)); }; } 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 test your code on a machine with big-endian architecture?

Both ideone.com and codepad.org have Little-Endian architechtures. I want to test my code on some machine with Big ... way that you 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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