Recent questions tagged C++

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c++ - How to check that an element is in a std::set?

How do you check that an element is in a set? Is there a simpler equivalent of the following code: myset.find(x) != myset.end() 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 char* to std::string

I need to use an std::string to store data retrieved by fgets(). To do this I need to convert the char* ... an array. How can this be done? 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 std::decay and when it should be used?

What are the reasons for the existence of std::decay? In what situations is std::decay useful? 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 I print the full value of a long string in gdb?

I want to print the full length of a C-string in GDB. By default it's being abbreviated, how do I force GDB to print the whole 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++ - problems with Move constructor and Move overloaded assignment operator?

Mostly all things explained by fredoverflow(user 237K Rep.) in his Two answers https://stackoverflow.com/a/ ... . please explain this point 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++ - Sobel derivative in OpenCV

I have been tasked with making my own Sobel method, and not use the cv::Sobel found in OpenCV. I ... wrong it would be greatly appreciated! 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++ - Excel VBA, Can't Find DLL Entry Point from a DLL file

I am attempting to use Excel VBA's ability to access and use functions from DLL files. example: Private Declare Function ... Add(1, 2) End Sub 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++ - order of evaluation of function parameters

What will be printed as the result of the operation below: x=5; printf("%d,%d,%d ",x,x<<2,x>>2) ... above as interview question on many sites. 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 install feature based on the property set in custom action?

I am trying to install one from two features based on the value that should be set inside of the custom ... do and would appreciate help. 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-braces-constructible type trait

How can I check whether specific type typename T is constructible from arguments typename ...Args in the ... significant loss of generality. 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++ - cin >> fails with bigger numbers but works with smaller ones?

Why does cin fail, when I enter a number like: 3999999999 but it works for smaller numbers like: 5 ? #include <iostream ... << n; 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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c++ - Cuda kernel returning vectors

I have a list of words, my goal is to match each word in a very very long phrase. I'm having no problem ... of solution? Thank you 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++ - Why Doesn't reinterpret_cast Force copy_n for Casts between Same-Sized Types?

According to cppreference.com, reinterpret_cast: Converts between types by reinterpreting the underlying bit pattern. But ... through this hoop? 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 nvcc fails to compile a CUDA file with boost::spirit?

I'm trying to integrate CUDA to an existing aplication wich uses boost::spirit. Isolating the problem, I've found out ... and how can I fix it? 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++ - Does this type of memory get allocated on the heap or the stack?

In the context of C++ (not that it matters): class Foo{ private: int x[100]; public: Foo(); } What ... 't find resources online to confirm 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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c++ - Why can't I do polymorphism with normal variables?

I'm a Java programmer and recently started studying C++. I'm confused by something. I understand that in C ... behavior, to help me understand. 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++ - Various questions about RSA encryption

I'm currently writing my own ASE/RSA encryption program in C++ for Unix. I've been going through the literature ... to read and answer, cheers! 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++ - Familiar template syntax for generic lambdas

For c++20 it is proposed to add the following syntax for generic lambdas p0428r2.pdf auto f = []<typename T>( T ... before '>' token f("Hello"); See Question&Answers more detail:os...

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

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319 views

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c++ - When does cout flush?

I know endl or calling flush() will flush it. I also know that when you call cin after cout, it flushes too. And also ... ++) { cout<<i<<endl; } See Question&Answers more detail:os...

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

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553 views

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c++ - Replace a line in text file

I want replace a line of text in a file, but I don't know a functions to this. I have this: ofstream ... Does C++ have functions for 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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343 views

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c++ - How to make cout behave as in binary mode?

Every time I do 'cout << endl' or even 'cout << " "' and then launch my program under Windows to output to a ... << " "'? Thanks in advance. See Question&Answers more detail:os...

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

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502 views

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c++ - Why is locking a std::mutex twice 'Undefined Behaviour'?

As per this article: If you try and lock a non-recursive mutex twice from the same thread without unlocking in ... why this has to be UB? See Question&Answers more detail:os...

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

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255 views

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c++ - adding list items or nodes in linked list

I try the following c++ code to sort linked list Items while inserting value from the keyboard. Here I want to insert ... = '5'); 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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c++ - I want to generate the nth term of the sequence 1,3,8,22,60 ,164 in Order(1) or order of (nlogn)

This sequence satisfies a(n+2) = 2 a(n+1) + 2 a(n). and also a(n)=[(1+sqrt(3))^(n ... for faster generation of this sequence? Please help 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++ - Paint a rect on qglwidget at specifit times

I'm using Qt 5.7 with c++ on ubuntu 16.04. I'm trying to implement a class that inherits qglwidget, ... drawn now). Would appreciate any help! See Question&Answers more detail:os...

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

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243 views

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c++ - Using boost::iostreams::mapped_file_source with std::multimap

I have a rather large amount of data to analyse - each file is about 5gigs. Each file is of the following ... expect to run into trouble there. See Question&Answers more detail:os...

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

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370 views

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c++ - What happens if I increment an array variable?

I know that it isn't safe to change a pointer's address if it lays on the heap because freeing it later would ... to a char array as a pointer. See Question&Answers more detail:os...

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

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332 views

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c++ - How to create NVIDIA OpenCL project

I want to write application in NVIDIA OpenCL in Visual Studio 2017 but don't know how to create project for ... in OpenCL in Visual Studio. See Question&Answers more detail:os...

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

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