std::to_string 函数的位置

Question

What is the reason std::to_string function is not a method of std::string class ? Because it would be logically more appropriate, isn't it? I want to know why they would not make it:

1. a static member function of std::string class

2. why would they not integrate it with constructor, so it would be possible to do like std::string ten( 10 ) and to get "10"?

Answer 1

C++ is not a OO language. You can write OO code in C++, but you can also not.

to_string is not written in an OO style.

There are advantages; the largest one is your code can choose to treat to_string as a customization point by doing

using std::to_string;
std::string foo=to_string(x);

and now any type that implements a to_string in its enclosing namespace works with the above code.

Also, to_string is arguably a method of both source and destination APIs; being a method of either is thus questionable.