Recent questions tagged C++

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c++ - Virtual destructor and undefined behavior

This question is different than 'When/why should I use a virtual destructor?'. struct B { virtual void ... behavior or well defined behavior? 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++ - Address of register variable

In C, we cannot use & to find out the address of a register variable but in C++ we can do the ... someone please explain this concept in-depth. 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++ - meaning of (number) & (-number)

What is the meaning of (number) & (-number)? I have searched it but was unable to find the meaning I want to use i & (-i ... = n; i += i & (-i)) 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 does sizeof do?

What is the main function of sizeof (I am new to C++). For instance int k=7; char t='Z'; What do ... sizeof (int) and sizeof (char) mean? 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 a vector of derived class pointers as base class pointers

In C++, the vector class stores an array of objects. In this case, I am storing pointers to derived ... argument vector(const vector& __x) ^ 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++ - Specialization of templated member function in templated class

I have a templated class with an templated member function template<class T> class A { public: template<class CT> CT ... ? Or is there a way? 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 does "operator = must be a non-static member" mean?

I'm in the process of creating a double-linked list, and have overloaded the operator= to make on list equal ... definition, with the "}". 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 compiler bug exposed by my implementation of an is_complete type trait?

I wrote this C++11 trait template to check whether a type is complete: template <typename...> using ... this particular construct 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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c++ - Try to understand compiler error message: default member initializer required before the end of its enclosing class

I try next code with three compilers (msvc2017, gcc8.2, clang7.0) and msvc2017 works all the way, but gcc ... compiler bug? 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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c++ - Is there any way to set a breakpoint in gdb that is conditional on the call stack?

I am debugging C++ in gdb 7.1 on Linux. I have a function a() that is called in many places in the code. I ... from c(), and so on ad infinitum? 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++ - <iostream> vs. <iostream.h> vs. "iostream.h"

When including a header file in C++, what's the difference between... 1) including the .h versus not ... "iostream.h" 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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c++ - Can a std::string contain embedded nulls?

For regular C strings, a null character '' signifies the end of data. What about std::string, can I have a string with embedded null characters? 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 any compiler barrier which is equal to asm("" ::: "memory") in C++11?

My test code is as below, and I found that only the memory_order_seq_cst forbade compiler's reorder. #include < ... Is there any better choice? 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++ - Linking g++ 4.8 to libstdc++

I downloaded and built gcc 4.8.1 on my desktop, running 64-bit Ubuntu 12.04. I built it out of ... rather than the system standard libraries? 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 can I set the decimal separator to be a comma?

I would like to read and write pi as 3,141592 instead of 3.141592, as using the comma is common in many ... print 3,141592 to standard output. 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 can I make GCC compile the .text section as writable in an ELF binary?

I would like to be able to dynamically change the executable code within a library I am using. Essentially, I would ... there a way to do 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++ - How do we explain the result of the expression (++x)+(++x)+(++x)?

x = 1; std::cout << ((++x)+(++x)+(++x)); I expect the output to be 11, but it's actually 12. 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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c++ - Override member field in derived classes

I have a code snippet below: #include <iostream> using namespace std; class Base { public: Base() : b( ... define its getter and setter? See Question&Answers more detail:os...

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

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450 views

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c++ - Is the data in nested std::arrays guaranteed to be contiguous?

Is the data in std::array<std::array<T,N>, M> guaranteed to be contiguous? For example: #include <array ... the entire matrix to be contiguous. 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 calling std::string.c_str() on a function that returns a string not work?

I have the following code: std::string getString() { std::string str("hello"); return str; } int main() { ... , when is str destroyed, and 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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236 views

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c++ - Standard-layout and tail padding

David Hollman recently tweeted the following example (which I've slightly reduced): struct FooBeforeBase { double d; ... of the above reasons) See Question&Answers more detail:os...

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

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289 views

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c++ - Detect when multiple enum items map to same value

Is there a compile-time way to detect / prevent duplicate values within a C/C++ enumeration? The catch is that there ... C and C++ is better. See Question&Answers more detail:os...

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

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264 views

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c++ - Why is protected constructor raising an error this this code?

One question about protected constructor. I learnt that the protected constructor can be used in the derived class. How ... working here } }; See Question&Answers more detail:os...

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

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340 views

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c++ - C++17 class template partial deduction

My understanding about the Template argument deduction for class templates proposal was to homogenize the behaviour of template ... 0.0 (trunk). See Question&Answers more detail:os...

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

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277 views

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c++ - Calling a const function rather than its non-const version

I tried to wrap something similar to Qt's shared data pointers for my purposes, and upon testing I found out ... there something I'm missing? See Question&Answers more detail:os...

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

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234 views

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c++ - undefined reference to `__stack_chk_fail'

Getting this error while compiling C++ code: undefined reference to `__stack_chk_fail' Options already tried: added -fno ... . Any help, please? See Question&Answers more detail:os...

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

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271 views

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c++ - is there an iterator across unique keys in a std::multimap?

Is there a simple or standard way to have a multimap iterator which iterate across unique keys in a multimap? i.e. ... point to {3, "angel"}? See Question&Answers more detail:os...

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

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1.1k views

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c++ - Correct printf format specifier for size_t: %zu or %Iu?

I want to print out the value of a size_t variable using printf in C++ using Microsoft Visual Studio 2010 (I ... seem very strange to me)? See Question&Answers more detail:os...

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

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