Pseudo code or description

Shell Programming and Scripting
1

hi I need a Pseudo code or a description of what a program is saying from this spec and code:
Just so i can understand how this solution was achieved, thanks

here is the spec:

Specifications are as follows:-

The books records are stored in one csv file and the layout and the contents are contained in File 1.
There are four categories of books: sports, computing, children's and horror. We should determine the category and then write a series of 3 records to the appropiate file.
The files need to be created in the program and their names will be: children, horror, sports and computing. The format of four files is contained in File 2.

Records which do not belong to any of the above categories should be printed to the screen as an error.

The summary report should be displayed on the screen and will contain the following information:

  • Date
  • names of files created (including path name)
  • total number of boks processed
  • total value of books

***************************
File 1 - CSV File sample
ISBN, Title, Category, cost, NO of copies
978-0340681138, Five Get into TRouble (Famous Five), Enid Blyton, Childrens, 6, 3
978-0142301883, The Little Match Girl, Hans Christian Anderson, Childrens, 3, 2
978-0304921532, cell, Stephen King, Horror, 7, 1
978-0596100292, Unix in a Nutshell Scripting, Arnold Robbins, Computing, 17, 2
****************
File 2 - Format of output files
ISBN: 978-0340681138
Author: Enid Blyton
Title: Five Get into Trouble (Famous Five)

And here is a model answer::

#!/usr/bin/perl
# classify_books.pl
my $csv_file   = shift;
my %categories = ( 'childrens' => 'childrens_books.txt',
                   'horror'    => 'horror_books.txt',
                   'sports   ' => 'sports_books.txt',
                   'computing' => 'computing_books.txt');

my @childrens_file, @horror_file, @sports_file, @computing_file;

open(CSV_FILE, '<', $csv_file)  or  die "Failed to read file $csv_file : $! \n";
while (my $line = <CSV_FILE>) {
    next unless ($line =~ m/^\d{3}-\d+,/);
    my ($isbn, $title, $author, $category) = split(/,/, $line);
    $title    =~ s/^\s+//;
    $author   =~ s/^\s+//;
    $category = lc($category);
    $category =~ s/^\s+//;

    unless (exists($categories{$category})) {
        print STDERR "\nUndefined category $category for book $title by $author having ISBN $isbn \n";
        next;
    }

    if ($category =~ m/childrens/) {
        push(@childrens_file, "ISBN: $isbn\nAuthor: $author\nTitle: $title\n\n");
    }
    elsif ($category =~ m/horror/) {
        push(@horror_file, "ISBN: $isbn\nAuthor: $author\nTitle: $title\n\n");
    }
    elsif ($category =~ m/sports/) {
        push(@sports_file, "ISBN: $isbn\nAuthor: $author\nTitle: $title\n\n");
    }
    elsif ($category =~ m/computing/) {
        push(@computing_file, "ISBN: $isbn\nAuthor: $author\nTitle: $title\n\n");
    }
}
close(CSV_FILE);

if (@childrens_file) {
    open (CHL_FILE, '>', $categories{'childrens'})  or  die "Failed to write file $categories{'childrens'} : $! \n";
    print CHL_FILE @childrens_file;
    close (CHL_FILE);
}

if (@horror_file) {
    open (CHL_FILE, '>', $categories{'horror'})  or  die "Failed to write file $categories{'horror'} : $! \n";
    print CHL_FILE @horror_file;
    close (CHL_FILE);
}

if (@sports_file) {
    open (CHL_FILE, '>', $categories{'sports'})  or  die "Failed to write file $categories{'sports'} : $! \n";
    print CHL_FILE @sports_file;
    close (CHL_FILE);
}

if (@computing_file) {
    open (CHL_FILE, '>', $categories{'computing'})  or  die "Failed to write file $categories{'computing'} : $! \n";
    print CHL_FILE @computing_file;
    close (CHL_FILE);
}

__END__
2

Sounds like homework. Also, please to not double post. And [code ][/code ] tags would help a lot...

3

so what if it is? nobody is born a genius I am working on it myself but a little help won't harm!

4

I'm not saying that we won't help you if it's homework, even if it's against the rules posting it, as long as you show some initiative. And asking for a complete code example, even if it's just pseudo-code, or asking for a complete rewrite isn't. I hope you understand that this isn't just my "attitude", it's just trying to treat everyone equal (everyone has to abide the rules here) and trying to help you (I found that a little explanation plus thinking for myself helps a lot more that a complete solution)

So, which parts of the code are hard to understand? Or is there any Perl concept that's hard to grasp?

5

ok sorry that we got off to a bad start, i understand most of the code, but in bash terms the middle bit is confusing, not sure what its trying to say, is it trying to define the categories of the book by reading the cvs file?

open(CSV_FILE, '<', $csv_file) or die "Failed to read file $csv_file : $! \n";
while (my $line = <CSV_FILE>) {
next unless ($line =~ m/^\d{3}-\d+,/);
my ($isbn, $title, $author, $category) = split(/,/, $line);
$title =~ s/^\s+//;
$author =~ s/^\s+//;
$category = lc($category);
$category =~ s/^\s+//;

and also does push in perl mean the same as path in bash?

6

No problem, as long as we both can leave that behind.

Comments are in blue, explaining the next line.

open(CSV_FILE, '<', $csv_file) or die "Failed to read file $csv_file : $! \n";
# As long as the file didn't end, read a whole line to the variable $line
while (my $line = <CSV_FILE>) {
    # Skip this line unless it begins (^) with 3 digits (\d{3}), a dash, and
    # one or more digits (\d+) up to a ','
    next unless ($line =~ m/^\d{3}-\d+,/);
    # Split the line on the comma, assigning the fragments to the variables
    # in the order they occured
    my ($isbn, $title, $author, $category) = split(/,/, $line);
    # Compress whitespaces
    $title =~ s/^\s+//;
    $author =~ s/^\s+//;
    # Convert to lowercase
    $category = lc($category);
    $category =~ s/^\s+//;

No. push in bash isn't even a builtin, but something provided by the distribution, so don't rely on it being there.
Perls push appends an element to the end of an array (opposite function would be pop, it's pretty simple to implement a stack with those two). Related are shift and unshift if you want to manipulate the start of the array.

If you need more details on a Perl function, call "perldoc -f <function>" on the command line, or look it up on perldoc.perl.org

7

ok, il take a look, thankyou

8

I think the forum rules are pretty clear:

(6) Do not post classroom or homework problems.