82. Smart Pointers-I

Question.7

A developer manages a file handle with a custom deleter:

auto deleter = [](FILE* f) { fclose(f); };
std::unique_ptr<FILE, decltype(deleter)>
   log_file(fopen("log.txt","w"), deleter);

fprintf(log_file.get(), "Boot OK");
// No fclose needed

What happens when log_file goes out of scope?

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The file is leaked -- unique_ptr only calls delete
The custom deleter (fclose) is called automatically, properly closing the file
Compilation error -- unique_ptr cannot manage FILE handles
The file is deleted from the filesystem

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