I am currently reading a file and storing the data in an array named @lines. Then, I loop through this array using a for loop and inside the loop I match on certain values:
$find = "fever"; if ($_ =~ /$find/) { print "$_\n"; $number++; #@lines = #print ("there are : " . $number); } At the moment, I am using a scalar, $find, with a value of fever instead of performing the repetitive statements for each filter.
Can I pass an array for comparison instead of a scalar keyword?
If you read a file into a list it will take everything at once
@array = <$fh>; # Reads all lines into array Contrast this with reading into a scalar context
$singleLine = <$fh>; # Reads just one line Reading the whole file at once can be a problem, but you get the idea.
Then you can use grep to filter your array.
@filteredArray = grep /fever/, @array; Then you can get the count of filtered lines using scalar, which forces scalar (that is, single value) context on the interpretation of the array, in this case returning a count.
print scalar @filteredArray; Putting it all together...
C:\temp>cat test.pl use strict; use warnings; # always my @a=<DATA>; # Read all lines from __DATA__ my @f = grep /fever/, @a; # Get just the fevered lines print "Filtered lines = ", scalar @f; # Print how many filtered lines we got __DATA__ abc fevered frier forever 111fever111 abc C:\temp>test.pl Filtered lines = 2 C:\temp> 
$filename. DATA is a new one on me, by the way, but I've never been more than a casual Perl user.If you have Perl 5.10 or later, you can use smart matching (~~) :
my @patterns = (qr/foo/, qr/bar/); if ($line ~~ @patterns) { print "matched\n"; } You could also use the File::Slurp module, which is convenient.
use strict; use warnings; use File::Slurp 'read_file'; my $fname = shift or die 'filename!'; my @lines = grep /fever/, read_file $fname; # grep with regular expression print @lines; If you're new to Perl, take a look at the map and grep operators, which are handy for processing lists.
Also, take a look at the ack utility, which is a great replacement for find/grep. (Actually, it's a superior alternative.)
Use Tie::File. It loads the file into an array, which you can manipulate using array operations. When you untie the file, its components will be saved back in the file.
