G'day Xhings,

That's not a good way to write your code at all. There's no correlation between $i, ..., $o and the elements in @patterns that each is associated with. You have to write separate code for every single one of those. It scales exceptionally poorly: what happens if need to add another keyword? What you really want is a hash whose keys are the keywords and values are the count.

There's other problems as well in the while loop: you only count the first occurrence of the first keyword in each line; the smartmatch operator (~~) is experimental and unsuitable for production code.

Here's some skeleton code you can use as a basis for rewriting your script:

$ perl -Mstrict -Mwarnings -le '
    my @eachline = (
        "transaction blah find blah blah think blah save_param",
        "start_sub blah url blah blah submit transaction blah find"
    );

    my @keywords = qw{transaction find think save_param start_sub url 
+submit};

    my $pattern = join("|" => map { "(?<$_>\\b$_\\b)" } @keywords);

    my %count;

    for (@eachline) {
        while (/$pattern/g) {
            ++$count{(keys %+)[0]};
        }
    }

    print "No. of matches for $_ is $count{$_}" for @keywords;
'
No. of matches for transaction is 2
No. of matches for find is 2
No. of matches for think is 1
No. of matches for save_param is 1
No. of matches for start_sub is 1
No. of matches for url is 1
No. of matches for submit is 1
[download]

See perlre if you're unfamiliar with named capture groups, i.e. (?<name>pattern).

Update: Reviewing this code on the following day, I think named capture groups was probably overkill in this situation. Here's a simpler version using ordinary captures:

$ perl -Mstrict -Mwarnings -le '
    my @eachline = (
        "transaction blah find blah blah think blah save_param",
        "start_sub blah url blah blah submit transaction blah find"
    );

    my @keywords = qw{transaction find think save_param start_sub url 
+submit};

    my $pattern = "(" . join("|" => map { "\\b$_\\b" } @keywords) . ")
+";

    my %count;

    for (@eachline) {
        ++$count{$1} while /$pattern/g;
    }

    print "No. of matches for $_ is $count{$_}" for @keywords;
'
No. of matches for transaction is 2
No. of matches for find is 2
No. of matches for think is 1
No. of matches for save_param is 1
No. of matches for start_sub is 1
No. of matches for url is 1
No. of matches for submit is 1
[download]