Recent questions tagged C++

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c++ - What information does GCC Profile Guided Optimization (PGO) collect and which optimizations use it?

Which information does GCC collect when I enable -fprofile-generate and which optimization does in fact uses the collected ... be a plus! =D 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 it ok to read a shared boolean flag without locking it when another thread may set it (at most once)?

I would like my thread to shut down more gracefully so I am trying to implement a simple signalling mechanism ... that proves the rule? 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++ - Convert a single character to a string?

Simple question (in C++): How do I convert a character into a string. So for example I have a string str = " ... & str[0]; Neither works. Ideas? 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++ - Checking if an iterator is valid

Is there any way to check if an iterator (whether it is from a vector, a list, a deque...) is (still) ... l.end()) { // blablabla } 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 bitwise shifts (<< and >>) used for cout and cin?

Question is in the title really; I'm sure there is something logical, but for now I'm stumped! 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 NULL undeclared?

I have a problem with this struct contructor when I try to compile this code: typedef struct Node { Node( int ... ::Blocks to compile this 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++ - Why does Boost.Asio not support an event-based interface?

I am attempting to understand Boost.Asio, with the intention of potentially implementing a signaling system ... really condition variables). 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++ - boost::asio and Active Object

I have implemented some module based Active Object design pattern. It is very simple implementation. I have Scheduler ... the wheel" once again. 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 the keyword "typename" needed before qualified dependent names, and not before qualified independent names?

class A { static int iterator; class iterator { [...] }; [...] }; I (think I) understand the ... different types, which is not acceptable." 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++ - Operator overloading on class templates

I'm having some problems defining some operator overloads for template classes. Let's take this hypothetical class for ... I doing wrong 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 does std::copy work with stream iterators

A usual STL construct is: vector<string> col; copy(istream_iterator<string>(cin), istream_iterator<string>(), ... ), istream_iterator<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++ - Why is copy constructor called instead of conversion constructor?

So basically this code: class A { }; class B { B (const B& b) {} public: B (){} B (const A& a) {} ... , but why? Where is this in the standard? 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++ - details of std::make_index_sequence and std::index_sequence

I'm enjoying ramping up on variadic templates and have started fiddling about with this new feature. I'm trying ... Think really dumbed down :) 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++ - (Partially) specializing a non-type template parameter of dependent type

Maybe I'm tired, but I'm stuck with this simple partial specialization, which doesn't work because non ... is this specialization even possible? 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 std::locale names are available on common windows compilers?

The standard is pretty much silent on what constitutes a valid locale name; only that passing an invalid locale name ... MSVC, MinGW, and ICC? 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++ - Return Type Covariance with Smart Pointers

In C++ we can do this: struct Base { virtual Base* Clone() const { ... } virtual ~Base(){} }; ... indeed doesn't compile, thanks to Iammilind 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 const_iterators faster?

Our coding guidelines prefer const_iterator, because they are a little faster compared to a normal iterator. It seems ... which both were equal. 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 inputs on one line

I have looked to no avail, and I'm afraid that it might be such a simple question that nobody dares ask it. Can one input ... >> a >> b >> c; 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++ - String literals not allowed as non type template parameters

The following quote is from C++ Templates by Addison Wesley. Could someone please help me understand in plain ... as template arguments either: 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 happens if 'throw' fails to allocate memory for exception object?

From C++11 standard (15.1.p4): The memory for the exception object is allocated in an unspecified way, ... ? Call std::terminate? Unspecified? 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++ - xxxxxx.exe is not a valid Win32 application

I have small C/C++ project in Visual Studio 2012 RC This applications parses the argv and then calling another ... > #include <direct.h> 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++ - How to alter a float by its smallest increment (or close to it)?

I have a double value f and would like a way to nudge it very slightly larger (or smaller) to get a new ... and not round back to the original. 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++ - invalid use of incomplete type

I'm trying to use a typedef from a subclass in my project, I've isolated my problem in the example below. ... : forward declaration of class B' 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++ - pop_back() return value?

Why doesn't pop_back() have a return value? I have Googled regarding this and found out that it makes it more ... making it so in the standard? 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 difference between the /Ox and /O2 compiler options?

Microsoft's C++ compiler (cl.exe, as included with Visual Studio) offers several optimization switches. The ... default option in VS? 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 OpenCV CUDA Functions from Python (No PyCUDA)

I am writing a Python application that uses OpenCV's Python bindings to do marker detection and other image ... OFF -DBUILD_opencv_xphoto=OFF .. 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 you read directly from physical memory?

In C or C++ (windows), how do you read RAM by giving a physical (not virtual) address? That means ... EDIT : added information about os. 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 take a screenshot correctly with xlib?

I am trying to capture an image of the screen for use in screencasting. Thus I need a fast solution, and cannot ... 8, blue_mask); 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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