cppreference.com > C++ I/O > eof eof Syntax:
      #include <fstream>
      bool eof();
The function eof() returns true if the end of the associated input file has been reached, false otherwise. For example, the following code reads data from an input stream in and writes it to an output stream out, using eof() at the end to check if an error occurred:
     char buf[BUFSIZE];
     do {
       in.read( buf, BUFSIZE );
       std::streamsize n = in.gcount();
       out.write( buf, n );
     } while( in.good() );
     if( in.bad() || !in.eof() ) {
       // fatal error occurred
     }
     in.close();
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