C++ Filehandling: Difference between ios::app and ios::ate?

Question

What\'s the difference between ios::ate and ios:app when writing to a file.
In my view, ios::app gives you the ability to move aro

Answer 1

It is pretty good documented here.

ios::ate "sets the stream's position indicator to the end of the stream on opening."

ios::app "set the stream's position indicator to the end of the stream before each output operation."

This means the difference is that ios::ate puts your position to the end of the file when you open it. ios::app instead puts it at the end of the file every time you flush your stream. If for example you two programs that write to the same log file ios::ate will override anything that was added to the file by the other program since your program opened it. ios:app will instead jump to the end of file each time your program adds a log entry.