class CStdioFile : public CFile
A CStdioFile object represents a C run-time stream file as opened by the run-time function fopen. Stream files are buffered and can be opened in either text mode (the default) or binary mode.
Text mode provides special processing for carriage return–linefeed pairs. When you write a newline character (0x0A) to a text-mode CStdioFile object, the byte pair (0x0D, 0x0A) is sent to the file. When you read, the byte pair (0x0D, 0x0A) is translated to a single 0x0A byte.
If you call these functions on a CStdioFile, you will get a CNotSupportedException.
For more information on using CStdioFile, see the articles Files in MFC and File Handling in the Run-Time Library Reference.