C++ Brain Teasers: Exercise Your Mind/

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Discussion: An Overloaded Container

Discussion: An Overloaded Container

Execute the code to understand the output and gain insights into constructor overloading and initialization.

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Run the code

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#include <initializer_list>
#include <iostream>
struct Container
{
    Container(int, int)
    {
        std::cout << "Two ints\n";
    }
    
    Container(std::initializer_list<float>)
    {
        std::cout << "std::initializer_list<float>\n";
    }
};
int main()
{
    Container container1(1, 2);
    Container container2{1, 2};
}

Understanding the output

The Container struct has two constructors, one taking two int types and one taking std::initializer_list<float>. Two objects of type Container are constructed, both with two int types as arguments. But the one difference is that one object is constructed using parentheses—(1,2)—and the other using curly braces—{1,2}. Which constructor is called in each case?

Constructor selection

For Container container1(1, 2), overload resolution unsurprisingly chooses the constructor that takes two ...