use strict; 
use warnings; 
use Data::Dumper; 
 
my $database = 'file.txt'; 
my (%hash,$input); 
open(Dbase,"<$database") or die "can't open $database $!"; 
while (my $line = <Dbase>){ 
chomp $line;  
my ($key,$val)=split('\s*:',$line); 
$hash{$key}=$val; 
} 
close Dbase; 
#print Dumper \%hash; 
open (DATA,"+>data.txt") or die "Can't open data"; 
do { 
	print "Enter reaction name for searching:"; 
	$input=<>; 
	chomp($input); 
	if(exists $hash{$input}) { 
    print DATA "$input,$hash{$input}\n"; 
	} 
	else { 
    print "Given Key isn't found in the file\n"; 
	} 
}until($input=~/^\s*$/); 
close(DATA);