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What is std::string and how does it differ from a C-string? What is std::string_view and why was it added? How do you convert between std::string and numbers? What common operations does std::string provide? How does std::string manage memory and what is SSO? How do you efficiently build up a large string? Why should you avoid returning std::string_view to local data? What is the difference between passing const std::string& and std::string_view? What is std::format (C++20) and how does it improve string formatting? How do you handle Unicode and encodings in C++ strings?
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What are the dangers of std::string_view?

Intermediate

Answer

Because string_view doesn't own its data, it dangles if the underlying string is destroyed or modified (e.g., a view of a temporary, or of a std::string that reallocates). You must ensure the referenced data outlives the view. Also, string_view isn't guaranteed null-terminated, so don't pass its data() to C APIs expecting a null terminator.
std::string_view v = std::string("temp"); // dangles: temporary destroyed
Real-world example A string_view returned from a function referencing a local string dangles and reads freed memory.

Common follow-ups: Why can a string_view dangle? | Is string_view null-terminated?

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All 11 Strings & string_view questions