I would code that like below without storing the paragraphs in arrays and definitive not in hashes. 
use strict;
use warnings;

my @string = ('String A', 'String B', 'String C', 'String D', 'String 
+E');
my @logfile = ('A.log', 'B.log', 'C.log', 'D.log', 'E.log');
my @logfh;

open (IN, '<', 'input.txt') or die "Couldn't open input file!\n";

for my $i (0..$#logfile) {
    open ($logfh[$i], '>', $logfile[$i]) or die "Couldn't create logfi
+le!\n";
}

local $/ = '';
while (my $paragraph = <IN>) {
    for my $i (0..$#string) {
        if ( index($paragraph, $string[$i]) >= 0) {
            print {$logfh[$i]} $paragraph;
        }
    }
}
close IN;

foreach my $fh (@logfh) {
    close $fh;
}

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This is for fixed strings. If you need regexes then replace the @string array with an array of regexes using qr{ } and replace the use of index with an regex call, ala $paragraph =~ $regex[$i].

In reply to Re: Parsing log file with blank lines for the field separator by mscharrer
in thread Parsing log file with blank lines for the field separator by JasonJ

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