Why is it not a good idea to close the file after every write statement and reopen it before the next write?

Question

Say U r writing a list of names to a file one name per write statement. Why is it not a good idea to close the file after every write statement and reopen it before the next write?

Answer 1

Think about it this way. If you had to make repeated trips, in succession, into your house, would you lock/unlock the door for every trip or just leave the door open until you were done? Working with reading/writing to a file is very similar in that you'll have a performance hit when opening/closing the file.