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The C++ Standard, [filebuf], paragraph 2 [ISO/IEC 14882-2014], states the following:

The restrictions on reading and writing a sequence controlled by an object of class basic_filebuf<charT, traits> are the same as for reading and writing with the Standard C library FILEs.

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No other std::basic_filebuf<T> function guarantees behavior as if a call were made to a standard C library file-positioning function, or std::fflush().

Note that calling Calling std::basic_ostream<T>::seekp() or std::basic_istream<T>::seekg() eventually results in a call to std::basic_filebuf<T>::seekoff() for file stream positioning. Given that std::basic_iostream<T> inherits from both std::basic_ostream<T> and std::basic_istream<T>, and std::fstream inherits from std::basic_iostream, either function is acceptable to call to ensure the file buffer is in a valid state before the subsequent IO I/O operation.

Noncompliant Code Example

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