默认赋值运算符在实际中是如何实现的 stl

Question

suppose we are implementing a vector class and we do

vector v;

v={1,2,3,4};

so,here we are implementing our own vector class so,how this list pass to assignment operator as an argument how we handle it because we passing constant which are not accessible by pointer variable and reference variable. But all this can be done in stl vector class, so how did they do?

Answer 1

Prior to C++17, all arguments to all functions name fully constructed objects.

A prvalue std::initialiser_list<int> object (with no name) is constructed from {1,2,3,4} , and that is the constructor's argument. That temporary object ceases to exist once v 's constructor ends (specifically at the end of the full expression that creates it).

From C++17 onward, a value that will initialise an object can be passed around. We still call it a prvalue std::initialiser_list<int> , but it isn't an object (yet). Somewhere in v 's initialisation, where it gets used, a std::initialiser_list<int> object is constructed. It also ceases to exist after the constructor is done.