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Perl for Web Site Management by John Callender

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Adding Categories to the Company Listings

The next step is to use that %categories_by_company hash that was populated in the &parse_category routine to add category links to the individual company listings, as stored in the %listing hash. Back in the main body of the script, after the part that reads through the category.txt file and runs the &parse_category routine on the lines read from it, we’ve added the following:

# append the category information to the company listings

foreach my $co_name (keys %listing) {

    if ($categories_by_company{$co_name}) {

Here we’ve got an outer foreach loop that cycles through all the company names in %listing (not bothering to put a sort in front of the keys function, since we don’t care about the order in which we process the companies). Inside that, we begin an if block that executes only if we have one or more categories listed in the %categories_by_company hash for this particular $co_name. In other words, we run the if block only for those companies that actually have categories.

Next, we use a function called split to turn the newline-separated list of company names stored in $categories_by_company{$co_name} into an actual list, and assign it to an array variable called @categories :

my @categories = split /\n/, $categories_by_company{$co_name};

The split function takes a first argument that is a regular expression pattern, and a second argument that is a string to be split. Then it splits the string wherever that regex matches and returns ...

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