Delete one character at End of File in PERL - html

Question

So I have encountered a problem while programming with PERL. I use a foreach loop to get some data out of the hash, so it has to loop through it.
The Code:
foreach $title (keys %FilterSPRINTHASH) {
$openSP = $FilterSPRINTHASH{$title}{openSP};
$estSP = $FilterSPRINTHASH{$title}{estSP};
$line = "'$title':{'openSP' : $openSP, 'estSP' : $estSP}\n";
print $outfile "$line\n";
}
The thing is, that I am creating a seperate File with the PERL's writting to a file expression, which will be a JSONP text (later used for HTML).
Back to the problem:
As JSONP requires comma's "," after every line that is not the last one, i had to put a comma at the end of line, however when the last line comes in, I have to remove the comma.
I have tried with CHOP function, but not sure where to put it, since if I put it at the end of foreach, it will just chop the comma in $line, but this wont chop it in the new file I created.
I have also tried with while (<>) statement, with no success.
Any ideas appreaciated.
BR

Answer 1

Using JSON module is far less error prone; no need to reinvent the wheel
use JSON;
print $outfile encode_json(\%FilterSPRINTHASH), "\n";

Answer 2

You can check if it is the last iteration of the loop, then remove the comma from line.
So something like
my $count = keys %FilterSPRINTHASH; #Get number of keys (scalar context)
my $loop_count = 1; #Use a variable to count number of iteration
foreach $title (keys %FilterSPRINTHASH){
$openSP = $FilterSPRINTHASH{$title}{openSP};
$estSP = $FilterSPRINTHASH{$title}{estSP};
$line = "'$title':{'openSP' : $openSP, 'estSP' : $estSP}\n";
if($loop_count == $count){
#this is the last iteration, so remove the comma from line
$line =~ s/,+$//;
}
print $outfile "$line\n";
$loop_count++;
}

Answer 3

i would approach this by storing your output in an array and then joining that with the line separators you wish:
my #output; # storage for output
foreach $title (keys %FilterSPRINTHASH) {
# create each line
my $line = sprintf "'%s':{'openSP' : %s, 'estSP' : %s}", $title, $FilterSPRINTHASH{$title}{openSP}, $FilterSPRINTHASH{$title}{estSP};
# and put it in the output container
push #output, $line;
}
# join all outputlines with comma and newline and then output
print $outfile (join ",\n", #output);