Getting filename (or path) from fstream

问题:

Can I get a file name or its path from a fstream object? I looked through the methods of fstream and didn't find anything close to it.

回答1:

No, that is not possible, not at least in the Standard conformant implementation of the library.

The fstream class doesn't store the filename, and doesn't provide any function for retrieving it.

So one way to keep track of this information is to use std::map as:

std::map<std::fstream*, std::string> stream_file_table;

void f()
{
  //when you open a file, do this:
  std::fstream file("somefile.txt");

  stream_file_table[&file] = "somefile.txt"; //store the filename

  //..
  g(file);
}
void g(std::fstream & file)
{
    std::string filename = stream_file_table[&file]; //get the filename
    //...
}

Or, simply pass around the filename as well.

回答2:

you may also design a little class which inherits from fstream and behaves like a fstream but also stores its file name.