Do I Need to Manually Close `std::ifstream` in C ?

Managing Resource Acquisition with std::ifstream and RAII

If you're working with file I/O in C , you may wonder whether you need to manually close an opened ifstream.

RAII and File I/O

The C Resource Acquisition Is Initialization (RAII) idiom simplifies resource management by ensuring that resources are automatically acquired and released when an object's lifetime begins and ends, respectively.

In the case of std::ifstream, RAII operates as follows:

• When an ifstream object is created, it acquires a file handle and associated resources.
• When the object's scope ends, its destructor is invoked, which automatically closes the file.

Do You Need to Close ifstream Manually?

No. Thanks to RAII, you do not need to manually call ifstream::close(). The destructor will handle this task for you.

Manual Closing Considered Harmful

Manually closing an ifstream is not the preferred C approach. It defeats the purpose of RAII by reintroducing potential resource leaks (if you forget to close the file) and race conditions (if the file is closed prematurely).

When to Manually Close

While RAII generally takes care of file closing, there may be instances where you need to close a file prematurely. In such cases, you can create a nested scope:

if (file.good()) {
  {
    std::stringstream buffer;
    buffer << file.rdbuf();
  } // File will be closed here

  return buffer.str();
}

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