Risks Using string_view

std::string_view was added into the Standard mostly to allow performance optimizations. Nevertheless, it’s not a replacement for strings! That’s why when you use views you have to remember about a few potentially risky things:

Taking Care of Not Null-Terminated Strings

string_view may not contain \0 at the end of the string. So you have to be prepared for that.

• string_view is problematic with all functions that accept traditional C-strings because string_view breaks with C-string termination assumptions. If a function accepts only a const char* parameter, it’s probably a bad idea to pass string_view into it. On the other hand, it might be safe when such a function accepts const char* and length parameters.
• Conversion into strings - you need to specify not only the pointer to the contiguous character sequence but also the length.

References and Temporary Objects

string_view doesn’t own the memory, so you have to be very careful when working with temporary objects.

In general, the lifetime of a string_view must never exceed the lifetime of the string-owning object.

That might be important when:

• Returning string_view from a function - the view has to point to that data that is still alive after the function has completed.
• Storing string_view in objects or containers - this is similar to storing pointers in a container. The referenced data must be still present when you access elements of this container.

---

To explore all these issues, let’s start with the initial example from this chapter.