Question

#include <fstream>

int _tmain(int argc, _TCHAR* argv[])
{
   std::ofstream F("con.txt", std::ios::out);

   F << "some text in con.txt";

   F.close();

   return 0;
}

output:

some text in con.txt

If i replace “con.txt” with “something.txt” then something.txt will contains the string “some text in something.txt.”

I think that the file con.txt bind with a console file… What is real happened in the first case?

Answer 1

CON is a reserved device name on Windows platforms. It shouldn’t be used as a file name, even with an extension.

From the documentation:

Do not use the following reserved
device names for the name of a file:
CON, PRN, AUX, NUL, COM1, COM2, COM3,
COM4, COM5, COM6, COM7, COM8, COM9,
LPT1, LPT2, LPT3, LPT4, LPT5, LPT6,
LPT7, LPT8, and LPT9. Also avoid these
names followed immediately by an
extension; for example, NUL.txt is not
recommended.