Using std::string_view with api that expects null-terminated string

Question

I have a method that takes std::string_view and uses function, which takes null terminated string as parameter. For example:

void stringFunc(std::experimental::string_view str) {
    some_c_library_func(/* Expects null terminated string */);
}

The question is, what is the proper way to handle this situation? Is str.to_string().c_str() the only option? And I really want to use std::string_view in this method, because I pass different types of strings in it.

Answer 1

You cannot alter a string through std::string_view. Therefore you cannot add a terminating '\0' character. Hence you need to copy the string somewhere else to add a '\0'-terminator. You could avoid heap allocations by putting the string on the stack, if it's short enough. If you know, that the std::string_view is part of a null-terminated string, then you may check, if the character past the end is a '\0' character and avoid the copy in that case. Other than that, I don't see much more room for optimizations.