40b04d6a_Ostream_Classes___Digital_Mars__Description
[Mode] ios::in [Description] 
Opens the file for input. Construction or opening of an ifstream always implies this bit; the bit need not be set. When set for an fstream, it means that input is allowed if possible. When set for an ofstream, it means that the file is not truncated when it is opened.
IOstream Classes - Digital Mars