Recent questions tagged C++

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c++ - Integer promotion - what are the steps

This code prints B2 short a=-5; unsigned short b=-5u; if(a==b) printf("A1"); else printf(" ... follows in widening/truncating the values? 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 change the name of a thread

I have a server application that uses "a lot" of threads. Without wanting to get into an argument about how ... me to customise that text. 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++ - Is the gettimeofday function thread safe in Linux?

The current time must be stored globally in order for gettimeofday to work, however I am not sure if ... concurrent execution is undefined. 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++ - Automatic constructor in explicitly instantiated class template

I have a template<bool VAR> struct Obj template declared in a header file (obj.h) with explicit automatic move ... 0 produce the same results.) 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 compile error using std::acos with clang++ not g++

I want to experiment with migrating a project from gcc to clang++. I admit ignorance on my part, I'm not sure why the ... with g++ (GCC) 5.2.0. 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 interrupt a waiting C++0x thread?

I'm considering to use C++0x threads in my application instead of Boost threads. However, I'm not sure ... workers cannot just sleep forever? 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++ - Compare typedef is same type

I am using C++ (not 11) and using some libraries which have different typedefs for integer data types. Is there any ... <UINT_32>()); // fail } 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++ - Is it safe to capture a member reference if the class storing the original reference goes out of scope?

Consider this: #include <iostream> #include <functional> std::function<void()> task; int x = 42; struct Foo { ... , have died. Is that right? 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 exactly happens when returning const reference to a local object?

struct A { A(int) : i(new int(783)) { std::cout << "a ctor" << std::endl; } A( ... But actually destructor is called before copy constructor) 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 access protected method in base class from derived class?

Here is a sample of code that annoys me: class Base { protected: virtual void foo() = 0; }; class Derived : ... ? Thanks for your help. :o) 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++ - writing into binary files

#include <iostream> #include <fstream> using namespace std; class info { private: char name[15]; char surname[15]; ... to hard for me to solve. 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++ - Given a word and a text, we need to return the occurrences of anagrams

Given a word and a text, return the count of the occurrences of anagrams of the word in the text. For eg ... 'm looking for a better complexity. 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 time complexity of std::map

What is the time complexity of std::map? And will it degenerate in the worst case? Or it is decide by the implementation, we can't know 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++ - Type undefined reference to `cv::fastFree(void*)'

I started the tutorial for opencv 2.4.7 on Win8, latest MinGW, and Eclipse Kepler R1, CDT. C++ Compiler includes ... /src line 23 C/C++ Problem 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 get an accurate 1ms Timer Tick under WinXP

I try to call a function every 1 ms. The problem is, I like to do this with windows. So I tried the ... maybe even found a solution? 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++ - Convert char* to uint8_t

I transfer message trough a CAN protocol. To do so, the CAN message needs data of uint8_t type. So I need ... and float. Thanks for your help. 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++ - specialize a member template without specializing its parent

I have a class template nested inside another template. Partially specializing it is easy: I just declare another ... attempt to make sense.) 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++ - performance of log10 function returning an int

Today I needed a cheap log10 function, of which I only used the int part. Assuming the result is floored, ... . Thank you on beforehand:) 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 the argument of the copy constructor a reference rather than a pointer?

Why is the argument of the copy constructor a reference rather than a pointer? Why can't we use the pointer instead? 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++ - Efficient computation of the high order bits of a 32 bit integer multiplication

Many CPUs have single assembly opcodes for returning the high order bits of a 32 bit integer multiplication. Normally ... like I'm looking for. 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 matching function call" in constructor

This is the constructor declaration that I have in my "solver.h" file. Solver(const Board &board_c, int max_moves_c) ... am compiling with g++. 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 int plus uint returns uint?

int plus unsigned int returns an unsigned int. Should it be so? Consider this code: #include <boost/static_assert.hpp> ... main() { return 0; } 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 instantiate an fstream if you declare it as a member of a class?

What constructor can you use to instantiate an fstream if you declare it as a member of a class? #include <fstream> ... here? myFile = ??? } 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++ - std::function instead of templates for predicates

Many standard library algorithms take predicate functions. However, the type of these predicates is an arbitrary, user- ... not much more clean? 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++ - Input from stream to enum type

How to input from stream to enum type? I can do it so unsigned int sex = 0; stream >> sex; student.m_bio.sex = static_cast<Sex>(sex); Otherwise? 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++ - friend class with inheritance

If I have two Classes as follows with inheritance: class A { ... } class B : public A { ... } And a ... B the friend Class in the first place? 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 an object created with placement new have dynamic storage duration?

(5.3.4) new-expression: ::opt_new new-placement_opt new-type-id new-initializeropt ::opt_new new- ... objects created with operator new 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++ - Eigen and boost::serialize

I tried to write a generic serialize function which takes any dense matrix and serializes it: Some other ... member named 'serialize'| See Question&Answers more detail:os...

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

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