my $SessionID = 2297;
my %hash;

my @files = qw(9524.pdf 8905.zip 5548.txt 146.txt 2297.doc
               814.htm 2069.zip 5358.zip 7800.rar);

foreach my $filename (@files) {
       my($base) = $filename =~ /(.+?)\..+?$/;
       $hash{$base} = $filename;
}

# printf("%s => %s\n", $_, $hash{$_}) for keys %hash;

print "$hash{$SessionID}\n";

# Ausgabe:
#2297.doc