Handle dangling string_view

Handling dangling std::string_view safely is crucial because using a std::string_view that references deallocated memory leads to undefined behavior. Here are some best practices to avoid dangling std::string_view:

Ensure String Lifespan

Make sure the original string outlives the std::string_view. Avoid returning std::string_view from functions that create local strings:

1#include <string_view>
2
3std::string_view getStringView() {
4  std::string temp{"Hello"};      
5  return std::string_view{temp};  
6}
7
8int main() {
9  std::string_view view = getStringView();
10}

The above code is problematic because temp is destroyed when the function exits, leaving view dangling. Instead, return the std::string itself:

1#include <string>
2#include <string_view>
3
4std::string getString() {
5  return std::string{"Hello"};
6}
7
8int main() {
9  std::string str = getString();
10  std::string_view view{str};  
11}

Use String Literals

For static strings, use string literals, which have static storage duration:

1#include <string_view>
2
3int main() {
4  std::string_view view{"Hello, world"}; 
5}

Avoid Temporary Strings

When initializing a std::string_view, ensure it doesn't refer to a temporary string:

1#include <string>
2#include <string_view>
3
4int main() {
5  using namespace std::string_literals;
6  std::string_view view{"Hello"s}; 
7}

Instead, use string literals or persistent strings:

1#include <string_view>
2
3int main() {
4  std::string_view view{"Hello"}; 
5}

By following these practices, you can avoid common pitfalls and ensure your std::string_view remains valid throughout its usage.