Recent questions tagged C++

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c++ - Is there a proper 'ownership-in-a-package' for 'handles' available?

Handles have proper semantics other than pointers. So for me an example like this (extracted from the Rule of Zero ... handling) Rule of Zero? 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 emulate _mm256_loadu_epi32 with gcc or clang?

Intel's intrinsic guide lists the intrinsic _mm256_loadu_epi32: _m256i _mm256_loadu_epi32 (void const* mem_addr); ... intrinsics available? 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++ - Reversing order of words in a sentence

#include <iostream> #include <cstring> using namespace std; void reverse(char* sentence) { int index = strlen(sentence ... error in my own 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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249 views

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c++ - Two colours text in QPushButton

I need a QPushButton with two colors in the text. I found a solution with a html code in QTextDocument and ... Any solution? Thank very much. 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++ - Forcing String to int Function to Consume Entire String

Given a string that should represent a number, I'd like to put it into a conversion function which would provide ... behavior on input "1X"? 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++ - Do I get a finished slot if I start QProcess using startDetached

Do I get a finished signal if I start a QProcess using startDetached()? I'm trying to start a process, ... when the process has terminated. 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::getline on std::cin

Is there any good reason why: std::string input; std::getline(std::cin, input); the getline call won't wait ... state of cin messed up somehow? 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 a case where including the same header twice is actually helpful?

Creating header guards for my h/hpp files has always been standard practice for me, but I wonder, why ... you actually need unprotected headers? 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++ - breaking out from socket select

I have a loop which basically calls this every few seconds (after the timeout): while(true){ if(finished) ... thread B can quit instantly? 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++ - Array of size defined by not constant variable

There is such code: #include <iostream> int main() { int size; std::cin >> size; size = size + 1; int tab3[size] ... ? I used g++ version 4.4.5. See Question&Answers more detail:os...

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

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185 views

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c++ - Capture __LINE__ and __FILE__ without #define

Trying to determine a "modern" implementation for the following C-style code: #define logError(...) log(__FILE__ ... logError was called from. See Question&Answers more detail:os...

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

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230 views

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c++ - Two '==' equality operators in same 'if' condition are not working as intended

I am trying to establish equality of three equal variables, but the following code is not printing the obvious correct answer ... ) == (j==k)) See Question&Answers more detail:os...

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

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350 views

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c++ - Calling constexpr in default template argument

In C++11 I am using a constexpr function as a default value for a template parameter - it looks like this: ... generated. Which one is correct? See Question&Answers more detail:os...

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

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426 views

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c++ - Turn off scientific notation on float

I'm trying to display number in standard notation for example: float f = 1230000.76 turns out to be, 1.23e+006 See Question&Answers more detail:os...

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

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233 views

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c++ - Static member access in constant expressions

Accessing static class member functions or variables, can be done in two ways: through an object (obj.member_fun( ... in a constexpr function? See Question&Answers more detail:os...

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

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173 views

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c++ - const auto std::initializer_list difference between Clang and GCC

I am trying to understand what the correct behavior of C++11 should be when combining initialization lists and const auto. I ... (3.4 and 3.6). See Question&Answers more detail:os...

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

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182 views

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c++ - Fallback variadic constructor - why does this work?

In answering this question about trying to construct a variadic forwarding reference constructor that should only be called if ... . Is it? Why? See Question&Answers more detail:os...

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

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408 views

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c++ - Undefined reference to mempcy@GLIBC_2.14 when compiling on Linux

I am trying to port an application to drive a device that uses an ftdi2332h chip from windows to linux. I ... guidelines on how to fix 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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259 views

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c++ - Simple std::regex_search() code won't compile with Apple clang++ -std=c++14

Here is the MCVE: #include <iostream> #include <regex> std::string s() { return "test"; } int main() { ... model: posix So, what's 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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168 views

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c++ - Why must an enumeration's size be provided when it is forward declared?

I just can't see why the size of the enumeration is relevant for the compiler while the size of the class ... this has not been standardized? See Question&Answers more detail:os...

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

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249 views

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c++ - Why can't I move std::ofstream?

Looking at previous answers on SO, it seems that while std::ostream is not be movable, std::ofstream should be ... work because of the above. See Question&Answers more detail:os...

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

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145 views

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c++ - std::tuple get() member function

boost::tuple has a get() member function used like this: tuple<int, string, string> t(5, "foo", "bar"); ... just my implementation (GCC 4.4)? See Question&Answers more detail:os...

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

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170 views

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c++ - Influence on the static scheduling overhead in OpenMP

I thought about which factors would influence the static scheduling overhead in OpenMP. In my opinion it is ... and critical section overhead. See Question&Answers more detail:os...

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

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188 views

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c++ - What is "bit padding" or "padding bits" exactly?

I do not want to molest you with this, but i just can not find anywhere in the internet a well-described ... much for any topic-based answer. See Question&Answers more detail:os...

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

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175 views

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c++ - error: expression must have a class type

I get the error: expression must have a class type Firstly, I don't understand why I am getting this error ... //returns the pieceworkers pay }; See Question&Answers more detail:os...

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

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141 views

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c++ - String-interning at compiletime for profiling

Context I am working on an instrumenting profiler, that enables you to name different measurements by string. So ... strings. Is this 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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321 views

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c++ - How to determine a region of interest and then crop an image using OpenCV

I asked a similar question here but that is focused more on tesseract. I have a sample image as below. I ... can perform to achieve the result? See Question&Answers more detail:os...

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

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101 views

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c++ - "__gfortran_pow_c8_i4" error when linking .o files from g++ and gfortran using g++

I am trying to link a .o file generated using g++ and another .o file generated using gfortran. g++ -c ... or subroutines in fortran in future. See Question&Answers more detail:os...

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

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