[Dev-C++] File Cursor Positon?

[Maya <Esc...@ne...>]

I am feeling very confused about this issue. What I want to do is to 
write a member function that will return the size of an std::fstream.
I have this:
const std::streampos getFileSize() {
     // get file size
     std::streampos file_size;
     std::streampos currentpos = f.tellg();
     f.seekg (0, std::ios::end);
     file_size = f.tellg();
     f.seekg (currentpos);
     return file_size;
}
  'std::istream::tellg()' would work if I open the stream for input, but 
would it work if I open the stream for output?

I want to avoid having to write two member functions, one for 
'std::istream' and another for 'std::ostream'. Is this possible?
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