The time to open and close the files is completely insignificant compared to the time to read them, especially if the files are large.

On the other hand, if the files are small, and you happen to open and close them lots of times, then you find out that the process of opening and closing is also very costly, compared to having memory-resident data that you just use over and over within loops. I would not consider the time taken to open and close files to be "completely insignificant".

In reply to Re^4: how to reset the input operater in while loop? by graff
in thread how to reset the input operater in while loop? by lightoverhead

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