fopen_s(&fp, "file.txt", "wb");。
Open in text (translated) mode. In this mode, CTRL+Z is interpreted as an end-of-file character on input. In files opened for reading/writing with
fopen_s checks for a CTRL+Z at the end of the file and removes it, if possible. This is done because using
ftell to move within a file that ends with a CTRL+Z, may cause
fseek to behave improperly near the end of the file.
Also, in text mode, carriage return–linefeed combinations are translated into single linefeeds on input, and linefeed characters are translated to carriage return–linefeed combinations on output. When a Unicode stream-I/O function operates in text mode (the default), the source or destination stream is assumed to be a sequence of multibyte characters. Therefore, the Unicode stream-input functions convert multibyte characters to wide characters (as if by a call to the
mbtowc function). For the same reason, the Unicode stream-output functions convert wide characters to multibyte characters (as if by a call to the
Open in binary (untranslated) mode; translations involving carriage-return and linefeed characters are suppressed.