$hash{$key}{$value}++;

my %hash = (); 
while (<FILE>) 
{ 
        s/\r|\n|//g; 
        s/#.*//; 
 
        #split the comma seperated values 
 
        ($FirstCol,$SecondCol) = split(/\,/) ; 
        $hash{$FirstCol}{$SecondCol}++; 
 
 } 
 
Close FILE;  
 
 # the next loop prints the keys/values of the hash 
        foreach $FirstCol (keys %hash) 
        { 
                 print "Key: $FirstCol, Value: $hash{$FirstCol}\n"; 
                } 
print "\n"; 
 
 
========================================== 
Output:  
Key: abc, Value: HASH(0x9cb5eb8) 
Key: xyz, Value: HASH(0x9cb5e94) 
 
 
It does not print abc-1,abc-2,abc-3 or xyz-1,xyz-2,xyz-3.

 
my %hash = ();  
while (<FILE>)  
{  
        s/\r|\n|//g;  
        s/#.*//;  
  
        #split the comma seperated values  
  
        ($FirstCol,$SecondCol) = split(/\,/) ;  
         push @{$hash{$FirstCol}}, $SecondCol; 
 
  
 }  
  
Close FILE;   
  
 # the next loop prints the keys/values of the hash  
        foreach $FirstCol (sort keys %hash)  
        {  
                 print "Key: $FirstCol, Value: @{$hash{$FirstCol}}\n";  
                }  
print "\n";  
  
 
Output:  
 
Key: abc, Value: HASH(0x8a528cc) HASH(0x8af8454) HASH(0x8af9809) 
Key: xyz, Value: HASH(0x8a4f374) HASH(0x8af97d4) HASH(0x8af9810)