Perl REGEX repetive capture groups when post processing output file

问题

I am dealing with a string of numbers in scientific format. for example

24  6.924E+06  8.316E-01  1.052E-01  1.622E+01  1.311E+01  0.000E+00  6.059E-06 (snip.. extends for a bit)

Now I want to write a regex for perl which allows me to capture the ith value in the list. So my current set up is the folloiwng

$_ =~ ^\s+\d+\s+(\d+[.]\d+E[+]\d+);
my $temp = $1;

Which will get me the first number. I want to be able to capture the 7th or the 50th if I wanted without having to write a really long regex expression.

is there a concise way of doing this?

Thanks in advance.

回答1:

use split

my @cols = split ' ', $_;

my $seventh = $cols[6];
my $fiftieth = $cols[49];

回答2:

split is the best option for this case.

my @val = split ' ', $_;
my $val7 = $val[6];

回答3:

An example for the third number:

^\s+\d+(?:\s+(\d+\.\d+E[-+]?\d+)){3}

When you repeat a capture group, the content is overwritten with the last match.

NB: in this case, it is more clean to use [0-9] instead of \d since you only need arabic digits.

来源：https://stackoverflow.com/questions/24833934/perl-regex-repetive-capture-groups-when-post-processing-output-file