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copy assignment operator in c++

Tired Tapir answered on January 30, 2022 Popularity 8/10 Helpfulness 4/10

answer copy assignment operator in c++

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copy assignment operator in c++

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#include <algorithm>
#include <iostream>
#include <memory>
#include <string>
 
struct A
{
    int n;
    std::string s1;
 
    A() = default;
    A(A const&) = default;
 
    // user-defined copy assignment (copy-and-swap idiom)
    A& operator=(A other)
    {
        std::cout << "copy assignment of A\n";
        std::swap(n, other.n);
        std::swap(s1, other.s1);
        return *this;
    }
};
 
struct B : A
{
    std::string s2;
    // implicitly-defined copy assignment
};
 
struct C
{
    std::unique_ptr<int[]> data;
    std::size_t size;
 
    // user-defined copy assignment (non copy-and-swap idiom)
    // note: copy-and-swap would always reallocate resources
    C& operator=(const C& other)
    {
        if (this != &other) // not a self-assignment
        {
            if (size != other.size) // resource cannot be reused
            {
                data.reset(new int[other.size]);
                size = other.size;
            }
            std::copy(&other.data[0], &other.data[0] + size, &data[0]);
        }
        return *this;
    }
};
 
int main()
{
    A a1, a2;
    std::cout << "a1 = a2 calls ";
  	a1.s1 = "Hello";
  	a2.s1 = "Murali":
    a1 = a2; // user-defined copy assignment
  	std::cout<<"a1.s1="<<a1.s1<<";a2.s1= "<<a2.s1<<endl;
 
    B b1, b2;
    b2.s1 = "foo";
    b2.s2 = "bar";
    std::cout << "b1 = b2 calls ";
    b1 = b2; // implicitly-defined copy assignment
 
    std::cout << "b1.s1 = " << b1.s1 << "; b1.s2 = " << b1.s2 << '\n';
}

Popularity 8/10 Helpfulness 4/10 Language cpp

Source: en.cppreference.com

Tags: c++

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Contributed on Nov 26 2023

Tired Tapir

0 Answers Avg Quality 2/10

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copy assignment operator in c++

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ClassName& operator=(const ClassName&);

Popularity 9/10 Helpfulness 3/10 Language cpp

Source: Grepper

Tags: c++

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Contributed on Jan 30 2022

Magnificent Millipede

0 Answers Avg Quality 2/10

copy assignment operator in c++

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