Programmatically determine if std::string uses Copy-On-Write (COW) mechanism

Question

Following up on the discussion from this question, I was wondering how does one using native C++ determine programmatically whether or not the std::string implementation they ar

Answer 1

Using &s1[0] to take the adress is not what you want, [0] returns a writable reference and will create a copy.

Use data() instead, it returns a const char*, and your tests may pass.

Answer 2

The copy-on-write paradigm is dependent on knowing when you are doing a write. This will occur whenever the object is returning a writable reference.

If you work with const references to the strings, you may be able to compare the addresses if the class was specialized to disable the copy when returning a const reference to the data.