I am trying to write a short program to convert some data in a rather bizarre format to something more useful.

The file contains n fixed width data fields (where n is known from the header of the file). Each line of the file contains up to three fields, so one record can run over more than one line, but each record starts on a new line. For example, if n=4, part of the file would look like this: 

           654           -0.1192052729835885D-03 -0.1074533611698108D+02
  0.2511576310952854D+05
           655           -0.1173814075917466D-03 -0.1074770905898570D+02
  0.2511659074419869D+05
           656           -0.1169565901326905D-03 -0.1074824015295493D+02
  0.2511670643648702D+05
           657           -0.1169057197333296D-03 -0.1074839256994435D+02
  0.2511658884706037D+05
           658           -0.1229838335208557D-03 -0.1074184682541694D+02
  0.2511451830545289D+05

I want to extract this data, and write it out with one record per line. All the data I have at the moment have n=4, so at the moment I am reading the entire multiline file into a single string, and breaking it up like this: 

# $data contains the entire contents of the input file
while ($data =~ /\s+ (\d+) \s+ (\S+) \s+ (\S+) \s+ (\S+)/gx) {
    print "$1  $2  $3  $4\n";
}

[download]

This works, but I don't see how to generalise it for variable values of n. Can anyone suggest how I might modify this fragment of code, or suggest an entirely different way of solving the problem?

Thanks in advance

In reply to Converting data from file with multiline records by Bilbo

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