in reply to Search Engine Output needs sorting

for (my $j=0; $j <= @grammatches; $j++) { ## Could be normal $j++ if u
+se another variable instead of @matches for both
...
    for (my $l=0; $l <= @headmatches; $l++) {
...
                for (my $m=0; $m <= @sentmatches; $m++) {

[download]

You have an off-by-one error on your for loops, you are trying to access one element past the end the arrays.    Those are usually written as: 

for my $j ( 0 .. $#grammatches ) { ## Could be normal $j++ if use anot
+her variable instead of @matches for both
...
    for my $l ( 0 .. $#headmatches ) {
...
                for my $m ( 0 .. $#sentmatches ) {

[download]

Replies are listed 'Best First'.
Re^2: Search Engine Output needs sorting
by Anonymous Monk on May 28, 2011 at 13:04 UTC

    Thanks for the insightful tip! However I'm not sure what that changes, since it was working before. Did I over compensate using the 'defined' function (which I used when I saw the uninitialized error)? <\p>

    I haven't encountered the $# before, does @ not work? Thanks again!

[reply]

      Using @array in scalar context gives the number of elements in the array whereas $#array gives the index of the last element.

      knoppix@Microknoppix:~$ perl -E '
> @array = ( 1 .. 5 );
> say qq{@array};
> say scalar @array;
> say $#array;'
1 2 3 4 5
5
4
knoppix@Microknoppix:~$

      [download]

      I hope this is helpful.

      Cheers,

      JohnGG

[reply]
[d/l]
[select]

        Thanks for clear explanation. Does ^# give the index of the first element? Don't why you'd need it, just curious.

[reply]

        Reply didn't work... Does ^# give first index? Don't know why you'd need, but curious.

[reply]
Re^2: Search Engine Output needs sorting
by Anonymous Monk on May 28, 2011 at 18:09 UTC

    Wait! Is that true for all for loops in Perl? You can never use the C-style method? I always have to use foreach or that .. operator instead?

[reply]

      You can never use the C-style method?

      I would not say never use -- there are instances where it might make better sense*. However, for simple (i=0;i<max;i++)-type loops, Perl has a different method of specifying it: for my $i (0..$max-1).

      This is a question of style and understanding. Just as not knowing idiomatic expressions (or using them incorrectly) can tag someone as "not from 'round here", using the C-style for loop in the general case may cause some to question how well you know Perl -- right or wrong.

      On the other hand (and this may be heresy), if you are in a C shop, and your coding standards are written from a C point of view, I suppose that could be an argument for using the C-style for loop. Not necessarily a good argument, but an argument.

      * - perhaps a time that you would want to use a C-style loop is if the increment is something other than 1, or if the exit test is something other than a simple comparison. However, this could be possibly written better in a different construct (while, for example).

      --MidLifeXis

[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom