Writing data to a file in C++ - most efficient way?

Question

In my current project I'm dealing with a big amount of data which is being generated on-the-run by means of a "while" loop. I want to write the data onto a CSV file, and I don't know what's better - should I store all the values in a vector array and write to the file at the end, or write in every iteration?

I guess the first choice it's better, but I'd like an elaborated answer if that's possible. Thank you.

Answer 1

Make sure that you're using an I/O library with buffering enabled, and then write every iteration.

This way your computer can start doing disk access in parallel with the remaining computations.

PS. Don't do anything crazy like flushing after each write, or opening and closing the file each iteration. That would kill efficiency.