赋值运算符（字符串）右侧的类型是什么？

Question

I am trying to understand how the assignment Operator knows what the data type of the right hand side of the Assignment Operator is.

string x = "foo"

Those are the Signatures I've found in the XCode Clang string file.

basic_string& operator=(const basic_string& str);
basic_string& operator=(basic_string&& str)
    noexcept(
         allocator_type::propagate_on_container_move_assignment::value &&
         is_nothrow_move_assignable<allocator_type>::value);
basic_string& operator=(const value_type* s);
basic_string& operator=(value_type c);
basic_string& operator=(initializer_list<value_type>);

Which one of these are invoked?

Any explanation appreciated!

Answer 1

The right hand side has type const char[4] , and the constructor

string(const char* s, const Allocator& alloc = Allocator());

is called, with the decay of const char[4] to const char* . See http://en.cppreference.com/w/cpp/string/basic_string/basic_string for a full list of constructors.

Note that initialization in the form T x = i; always calls a constructor, not an assignment operator. A constructor gives an object its initial value, whereas an assignment operator replaces a value that already existed in an object.