Recent questions tagged C++

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c++ - Renaming first and second of a map iterator

Is there any way to rename the first and second accessor functions of a map iterator. I understand they have these ... to have it->vertex } 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++ - Where in a declaration may a storage class specifier be placed?

For example, let's consider the static storage class specifier. Here are a few examples of both valid and ... standard and explain them. 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++ - Saving a stream while playing it using LibVLC

Using LibVLC, I'm trying to save a stream while playing it. This is the python code: import os import ... but not duplicate, topic yesterday. 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++ - Getting enum names (e.g. CV_32FC1) of OpenCV image types?

In the C++ interface to OpenCV, it seems easy enough to check the type of an image. If you have an image ... integer value of the OpenCV enum? 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++ - constexpr global constants in a header file and odr

Unfortunately, I am somewhat confused about constexpr, global constants declared in header files, and the odr. In short ... how I use them? 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++ - Nested Template Specialization

Having a brain fart... Is it possible to make something like this work? template<int a> struct Foo { ... by the language. AFAICS, anyway. 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 is the size of a socket send buffer in Windows?

Based on my understanding, each socket is associated with two buffers, a send buffer and a receive buffer, ... operations) work under Windows? 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++ - QtWebEngine debugging

Recently Qt introduced the QtWebEngine module. Is there a way to invoke developer tools and debug JavaScript ... option in QWebEngineView. 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 variadic std::function parameter

A function named test takes std::function<> as its parameter. template<typename R, typename ...A> void test( ... stated and stateless) as well. 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++ - Android Studio "Current NDK support is deprecated"

As of Jan 2015 the NDK support for Android studio is still unusable. A cryptic message says: "Alternative will be ... with the release of 1.3 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++ - Windows SDK registry variable not found

I cannot build my project in Visual Studio 2012. The error is: 1>C:Program Files (x86)MSBuildMicrosoft.Cppv4 ... Windows SDK but neither helped. 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't stream std::endl with overloaded operator<<() for std::variant

This answer describes how to stream a standalone std::variant. However, it doesn't seem to work when std::variant ... is it possible to fix 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 happens when using make_shared

I'm interested if these two lines of code are the same: shared_ptr<int> sp(new int(1)); // double ... one allocation in the second line? 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++ - When are header-only libraries acceptable?

Personally, I quite like header-only libraries, but there are claims they cause code bloat due to over-inlining (as ... have tagged it as such. 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 cast a pointer to a reference?

Originally being the topic of this question, it emerged that the OP just overlooked the dereference. ... Explanations? Standard quotes? 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++ - map of vectors in STL?

I want to have a map of vectors, (but I don't want to use pointer for the internal vector), is it possible? / ... * >(10, new vector<MyClass>)); 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++ - Qt drawing a filled rounded rectangle with border

I want to draw a rectangle with rounded corners (border radius same for all 4 corners) with a specific color ... have to do anything else? 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++ - Relocation R_X86_64_32S against `.rodata' ... While compiling on 64-bit platform

So I've been coding something on 32-bit and yesterday I needed to build a dll and I had a couple of ... been unable to figure this out. 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 does changing `const ull` to `const ull&` in function parameter result in performance gain?

So with the following code, changing the type of the parameter x from const ull to const ull& (with typedef ... /value Took 1.83seconds total. 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 a string contains only alphanumeric characters (or a space)

I am writing a function that determines whether a string contains only alphanumeric characters and spaces. I am effectively ... way to do 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++ - Predefined Macros for function name __func__

I am attempting to build a debug log message function that records the file, line, and function of of where the ... if a __func__ can be used? 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 __func__, __FUNCTION__ and __PRETTY_FUNCTION__ aren't preprocessor macros?

I've just noticed that __func__, __FUNCTION__ and __PRETTY_FUNCTION__ aren't treated as preprocessor macros and they' ... behind this decision? 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++ - Implementing variadic min / max functions

I'm implementing variadic min/max functions. A goal is to take advantage of the compile time known ... efficiency of template metaprogramming) 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++ - Speeding up build process with distutils

I am programming a C++ extension for Python and I am using distutils to compile the project. As the project ... /gist.github.com/2923577 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++ - Add same value multiple times to std::vector (repeat)

I want to add a value multiple times to an std::vector. E.g. add the interger value 1 five times to the vector: ... a clean c++ way to do 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++ - Do class methods increase the size of the class instances?

The question is pretty straight forward. For clarity, consider the example below: // Note that none of the ... longer than Bar, theoretically? 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++ - Does multithreading emphasize memory fragmentation?

Description When allocating and deallocating randomly sized memory chunks with 4 or more threads using openmp's parallel for ... and 4.6(trunk). 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++ - LINK : fatal error LNK1561: entry point must be defined ERROR IN VC++

I installed MS VS VC++ for the first time in order to start programming OpenGL with GLFW library. I ... the installation process or something. See Question&Answers more detail:os...

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

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