logo
Tags down

shadow

Why can't a destructor have reference qualifiers?


By : Silas
Date : August 01 2020, 10:00 AM
I hope this helps you . First, there must be only one destructor per class. Allowing ref-qualifiers on the destructor would make it possible to overload the destructor.
Another possible reason is to be consistent with const and volatile qualifiers:
code :


Share : facebook icon twitter icon

Template Reference Collapsing Dropping cv-qualifiers for const Reference Return Type


By : user3513771
Date : March 29 2020, 07:55 AM
Hope that helps You could use std::remove_reference to drop the reference and add it back:
code :
#include <type_traits>

template<typename T>
class Raw
{
    T obj;
    using NR = std::remove_reference_t<T>;

public:
    Raw() {};
    Raw(const T& init): obj(init) {};

    NR& get() {return obj;};
    const NR& get() const {return obj;};
};

What are reference qualifiers for functions?


By : user3865130
Date : March 29 2020, 07:55 AM
hop of those help? According to this webpage, a non-static member function can have a trailing & or && in its declaration. They have the following example
code :
struct S {
  virtual int f(char) const, g(int) &&;
};

struct D : S {
  virtual int f(char) const override;
  virtual int g(int) && override;
};

Binding to reference of type discards qualifiers


By : Coolieo
Date : March 29 2020, 07:55 AM
seems to work fine std::map makes its keys immutable, so references to mutable versions of its keys is not possible without violating const-correctness. If you are certain that this version of a map where you're doing lookups by value is correct, then you'll need to roll your own data structure to make this code work.
Alternatively, because I have difficulty believing that that's actually a correct version of your program, consider the following: in all instances where you look-up values in edges, you're searching for a std::string associated with two Tnode objects. It seems pretty clear that the correct data structure for this code is not std::map>, but std::map, Tedge>. Tnode in this case represents half of the key looking up a Tedge object, which is how you use it.
code :
void add(Tnode n, Tnode n2, Tedge e) {
    edges.insert(std::make_pair(std::make_pair(n, n2), e));
}

bool has(Tedge edge) const{
    bool l = false;
    for(typename std::map<Tedge, std::pair<Tnode, Tnode>>::const_iterator it = edges.begin(); it != edges.end() && !l; it++) {
        l = it -> second == edge;
    }

    return l;
}

const Tedge operator()(const Tnode &first, const Tnode &sec) const {
    std::map<std::pair<Tnode, Tnode>, Tedge>::const_iterator it = edges.find(std::pair<Tnode, Tnode>(first, sec));
    if(it != edges.end()) 
        return it-> second;
    else
        throw std::runtime_error("No such element found");
}

Tedge & operator()(const Tnode &first, const Tnode &sec) {
    std::map<std::pair<Tnode, Tnode>, Tedge>::iterator it = edges.find(std::pair<Tnode, Tnode>(first, sec));
    if(it != edges.end()) 
        return it-> second;
    else
        throw std::runtime_error("No such element found");
}
void add(Tnode n, Tnode n2, Tedge e) {
    edges.emplace(std::make_pair(n, n2), e);
}

bool has(Tedge const& edge) const{
    for(auto const& entry : edges) 
        if(entry.second == edge) 
            return true;
    return false;
}

const Tedge operator()(const Tnode &first, const Tnode &sec) const {
    if(auto it = edges.find(std::make_pair(first, sec)); it != edges.end())
        return it->second;
    else
        throw std::runtime_error("No such element found");
}

Tedge & operator()(const Tnode &first, const Tnode &sec) {
    if(auto it = edges.find(std::make_pair(first, sec)); it != edges.end())
        return it->second;
    else
        throw std::runtime_error("No such element found");
}

Why derived class destructor called even though base class destructor is not virtual if object is created as reference


By : Mohamed Hassan
Date : March 29 2020, 07:55 AM
Any of those help This is a special case when const references to temporaries are involved. The destructor for the temporary is correctly invoked, rather than the destructor of the reference since, after all, the lifetime of the temporary is merely extended.

C++98/03 reference collapsing and cv qualifiers


By : Bruno
Date : March 29 2020, 07:55 AM
To fix this issue GCC 4.7.2 does not compile this when the flag -std=c++98 is specified. In fact, in C++98 (as well as in C++03) references to references do not collapse.
An attempt to instantiate f, where T = int&, produces the following function signature (here I intentionally switch the position of the argument type T and the const specifier, which is allowed because const T& is the same as T const&):
Related Posts Related Posts :
  • How can I store all data the user inputs and then show them if they want to see all of them
  • Use depth texture in compute shader
  • error: conflicting declaration using universal references
  • Using std::optional instead of own structure
  • Is it necessary to make pointer Null when there is no use of it at the end in c++
  • How are std::array's compared in C++?
  • Herb Sutter's article on making virtual functions private
  • Interaction between copy-and-swap idiom and move operations
  • Problems using overloaded extraction operator in C++
  • segmentation fault on reading certain files, seems to be unrelated to filesize
  • Protected members of base classes inaccessible to friends of derived classes
  • Constructing smart pointer from stack allocated raw pointer
  • Array Index Overload Bug
  • Why I'm getting " void value not ignored as it ought to be"?
  • Need help converting a string to a char in c++ ---- ERROR A value of type "const char *" cannot be used to ini
  • What means put preprocessor in std::string?
  • Is it possible to compare an array elements with a hard-coded initializer list without loop?
  • Complexity of an specific algorithm with 3 for?
  • Character converting funtion std::isupper() & std::islower() C++17
  • Hide method taking template parameter reference in cpp file
  • Disable the std::initializer_list constructor
  • What does "static_cast<double>(123)" mean in C++?
  • How to use libraries (*.a files) in C++ when using cmake
  • Use class name for conditional macro expansion
  • C++ variable names (can declare main as variable however same is not true for other functions name)
  • error: ‘nullptr’ was not declared in this scope
  • Why is the z coordinate flipped after multiplying with a matrix in GLSL - OpenGL
  • QML use C ++ function with parameters
  • How can I convert a character from a string into a integer variable using C++
  • Can range-v3 contains work on initializer list?
  • How would I calculate the runtime of this function?
  • Is there a way to produce random numbers simultaneously in c++? If not, is there a work around?
  • How do you create a dynamic array for struct elements of different variable types for c++?
  • Subclass address equal to virtual base class address?
  • _mm_xor_pd fails with product = 0
  • I got a stack overflow error in my int main()
  • Why does imwrite on BMP image gets stuck / does not return?
  • Why program throws runtime error while iterating over an emtpy vector in c++
  • Unknown error while debugging a QT-application with Visual Studio Code and CMake-Tools
  • Is `string.assign(string.data(), 5)` well-defined or UB?
  • Modern way to have a map that can point-to or reference data of different types that has been allocated on the stack
  • Why does my recursive function print in descending order and then in ascending order?
  • Fill vector with true value
  • Automate "yes" to Popen SSH command
  • warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
  • What is wrong in this C++ code snippet with template<class Vector>
  • Printing hollow square with array
  • Overload -> arrow operator in shared_ptr<interface> instance with no pure virtual destructor in interface
  • Run thread with derived method from base class without using templates
  • Issues with template class conversion - unable to deduce function called
  • How is memory deallocated in c++
  • is it possible to reduce delete code size with templates in C++
  • How to resolve Ninja c++ build and execution
  • Trying to control multithreaded access to array using std::atomic
  • Checking which object called the other's object method
  • How do we run a single test using Google bazel
  • Should I add other files to git except .cpp?
  • Idiom for handling size_t underflow in loop condition
  • What is Kotlin for C++ push_back() and pop_back() on a string?
  • Tree implementation in C++: Cannot convert Node to int* Ask Question
  • shadow
    Privacy Policy - Terms - Contact Us © voile276.org