c++ - What is the meaning of following syntax:: fstream myFile("test.txt", ios::in | ios::out | ios::trunc);

Question

fstream myFile("test.txt", ios::in | ios::out | ios::trunc);

How is this line interpreted by the compiler in C++ file handling?

Answer 1

ios::out means that you intend to write to the file in contrast to reading ios::in. In your case the stream can be used for both reading and writing.

ios::trunc means that the current file content will be discarded. Compare this to ios::app where you will append to a file if it exists. ios::trunc is implied if not ios::in is specified for example. "When used for an ofstream without ios::app, ios::ate or ios::in, ios::trunc is implied."

Bonus:

iso::binary means that what you will write will be put verbatim into the file (otherwise for windows could be replaced with for example)