12.4) File Modes
File opening mode can be specified as a second argument when creating an ifstream
, ofstream
or fstream
object.
C++ provides a set of mode constants, including:
ios::binary
to indicate that a file should be opened in binary modeios::trunc
to indicate that any existing contents of an output file should be discarded (the default when opening files for output)ios::ate
to indicate that a stream's position indicator should be put at the end of existing content after openingios::app
to indicate that a stream's position indicator should be put at the end of existing content before each write
The value used for mode is a bitwise OR of the desired constants:
ofstream outfile("data.bin", ios::ate | ios::binary);
See the page on open
at cppreference.com for further information.