Difference between string.empty and string[0] == '\0'

Question

Suppose we have a string

std::string str; // some value is assigned

What is the difference between str.empty() and str[0] =

Answer 1

Since C++11 it is guaranteed that str[str.size()] == '\0'. This means that if a string is empty, then str[0] == '\0'. But a C++ string has an explicit length field, meaning it can contain embedded null characters.

E.g. for std::string str("\0ab", 3), str[0] == '\0' but str.empty() is false.

Besides, str.empty() is more readable than str[0] == '\0'.