Recent questions tagged C++

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c++ - How do I strip a tuple<> back into a variadic template list of types?

Is there a way to strip a std::tuple<T...> in order to get it back to T...? Example Suppose vct< ... the actual values of a tuple instance. 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++ - return by value assigned to const reference

I was fixing another bug in some code and came across some code that I would have thought was a bug; ... the rationale behind this being legal? 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++ - Binding to a weak_ptr

Is there a way to std::bind to a std::weak_ptr? I'd like to store a "weak function" callback that ... a fix for it) weak_fn Another weak_fn 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++ - Detecting SSD in Windows

I would like to change the performance and behaviour of my C++ application, according to whether the system drive is ... is an SSD or not? 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 would the conversion between derived* to base* fails with private inheritance?

Here is my code - #include<iostream> using namespace std; class base { public: void sid() { } }; class ... ? Can someone please explain 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++ - Simplest way to write output message to 'output window' in Visual Studio 2010?

I've tried OutputDebugString function and most of the time I get error like : error C2664: 'OutputDebugStringA' ... ' Please suggest. 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 to use c union nested in struct with no name

I'm working on the so called Hotspot open source project, and looking at the implementation I found a nasty ... and for what purpose? 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++ - Copy a std::vector to a repeated field from protobuf with memcpy

At first I have this simple protobuf file message messagetest { ... repeated float samples = 6; .... } Which ... no idea how to implement 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++ - why derive from a concrete class is a poor design

I was reading about NonVirtual Interface pattern: Herb Sutter is talking about why virtual function must be private in ... this is a poor design 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++ - difference between interface inheritance and implementation inheritance

I found those two terms in the book of Meyers, but what is the difference? 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++ - Putting class declaration in .cpp file

Is it possible to have class declaration and implementation in same .cpp file? I want to do some unit ... from ConnectionMockup it works. 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 share HWND between 32 and 64 bit applications in Win x64?

MSDN tells me that handles to windows (HWND) can be shared between 32- and 64-bit applications, in ... , semaphores and file handles. 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++ - Move-assignment and reference member

Copy-assignment for a class with a reference member variable is a no-no because you can't reassign the reference. ... , C&) hard to implement. 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++ - "if" block without curly braces makes subsequent "else if" nested

AFAIK, if an "if" block is not provided the curly braces then only 1 statement is considered inside it. e. ... without braces and with braces]. 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++ - Creating a copy constructor for a linked list

This is homework I'm working on implementing a linked list class for my C++ class, and the copy constructor has ... didn't run into any issues. See Question&Answers more detail:os...

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

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206 views

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c++ - Weird compiler error: Cannot convert parameter from 'int' to 'int &&'

What on earth is going on here? I'm trying to create a pair of an int and a string and I can create the pair if ... I say, I just don't get 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++ - What are some 'good use' examples of dynamic casting?

We often hear/read that one should avoid dynamic casting. I was wondering what would be 'good use' examples of ... that I asked my 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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c++ - Valid Locale Names

How do you find valid locale names? I am currently using MAC OS X. But information about other ... _S_create_c_locale name not valid Abort 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 hide an implementation helper template?

Suppose that I have two template functions declared in a header file: template <typename T> void func1(const T& ... to hide the helper function? 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 a const key for unordered_map

I've been switching my code over from std::map to std::unordered_map where appropriate. With std::map, I ... key for any associative container? See Question&Answers more detail:os...

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

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448 views

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c++ - pthread sleep linux

I am creating a program with multiple threads using pthreads. Is sleep() causing the process (all the threads) to ... where I am calling sleep? See Question&Answers more detail:os...

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

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557 views

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c++ - Why is it faster to perform float by float matrix multiplication compared to int by int?

Having two int matrices A and B, with more than 1000 rows and 10K columns, I often need to convert ... BLAS integer matrix operations exist. 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++ - Forcing the Qt GUI to update before entering a separate function

This seems like it should be automatic, but apparently it's not. I have the following code: ui.my_label-> ... it enters that function? 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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271 views

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c++ - __FILE__ macro manipulation handling at compile time

One of the issues I have had in porting some stuff from Solaris to Linux is that the Solaris compiler expands the ... think? Can it be done? 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++ - No RTTI but still virtual methods

C++ code can be compiled with run-time type information disabled, which disables dynamic_cast. But, virtual ( ... able to always work? 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 pointers be totally ordered?

Pointers in C++ may in general only be compared for equality. By contrast, less-than comparison is only ... on all their supported platforms. See Question&Answers more detail:os...

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

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357 views

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c++ - End iterator invalidation rules

Regarding this question on iterator invalidation rules, it seems obvious that the spirit of the standard means, ... make this clear somewhere? See Question&Answers more detail:os...

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

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715 views

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c++ - How to get the SHA-1/MD5 checksum of a file with Qt?

Is there a way to get the MD5 or SHA-1 checksum/hash of a file on disk in Qt? For example, I have ... that file matches a certain hash value. See Question&Answers more detail:os...

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

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