Why do you want to process all the records of one type first rather than build 9 arrays as you move through the file and then sort and output then at the end?

I think the missing peices of information from your question are:

a) How big is the input file?

b) Is the input file pre-sorted by the first field? ie. will all the "5 x x x x x x x x" lines be contiguous in the input file?

If the input file is not pre-sorted and especially if it is large, then it would probably be faster to use the system utility to pre-sort the input file, or a copy of it if you need to preserve the original.

If your reasons for doing one record type at a time is because each subset if very large, then it may well be quicker to process the input file to 9 output files in one pass and then either reload the 9 files sort and output again, or use the sort utility on them.

A clear picture of the scale of the problem would make the choice of solution easier.

In reply to Re: How can I read multiple lines starting with the same number and put in to a nested array and print it to a file? by BrowserUk
in thread How can I read multiple lines starting with the same number and put in to a nested array and print it to a file? by opolat

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