Do I need to manually close an ifstream?

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NO

This is what RAII is for, let the destructor do its job. There is no harm in closing it manually, but it’s not the C++ way, it’s programming in C with classes.

If you want to close the file before the end of a function you can always use a nested scope.

In the standard (27.8.1.5 Class template basic_ifstream), ifstream is to be implemented with a basic_filebuf member holding the actual file handle. It is held as a member so that when an ifstream object destructs, it also calls the destructor on basic_filebuf. And from the standard (27.8.1.2), that destructor closes the file:

virtual ˜basic_filebuf();

Effects: Destroys an object of class basic_filebuf<charT,traits>. Calls close().

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