The reason your attempt at substr doesn't work, this part 

   while (my $elements[20] = <INFILE>) {
        substr $elements, 7, 0, ' ';
        }

[download]

is simple, files are iterators, once you read the whole file, this part of your code  @infile=<INFILE>;

you're at the very end, there is no more file left to read

Also that is a syntax error

You probably meant to write 

substr $elements[20], 7, 0, '  ';

[download]

You ought to give perlintro another read

 if ($#ARGV != 1) {print "usage: input-file output-file \n";exit;}

In perlish perl we write that as :) 

@ARGV or die "Usage: $0  input-file output-file\n";

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You can write it as  if( @ARGV  ){ die "Usage: $0  input-file output-file\n"; } if you're attached to if(){}

In reply to Re^2: Add whitespace in middle of string (substr?) by Anonymous Monk
in thread Add whitespace in middle of string (substr?) by Janwhatever

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