为什么 text.size() 返回 std::size_t 而不是 std::string::size_type

Question

I am studying c++ and currently reading C++ Primer (5th ed). I am on the topic about std::string . The size member returns the length of the string. The book says (p. 88)

auto len = line.size(); // len has type string::size_type

But Visual Studio Code identifies len as having the type std::size_t . Why is it different?

Answer 1

identifies len as having the type std::size_t . Why is it different?

From microsoft's basic_string documentation :

typedef typename allocator_type::size_type size_type;

Remarks

it's equivalent to allocator_type::size_type .

For type string , it's equivalent to size_t .

(emphasis mine)

Thus, as can be seen from the above quoted remark, for std::string , it is equivalent to size_t .