Re: Fields won't add when reading a text file
- From: Tad McClellan <tadmc@xxxxxxxxxxxxxx>
- Date: Sat, 29 Apr 2006 22:40:09 -0500
NevadaSam@xxxxxxxxx <NevadaSam@xxxxxxxxx> wrote:
In learning CGI/Perl
Learning two things at once makes it more than twice as hard.
It will be easier if you learn one at a time.
Start with learning Perl.
Learn your application area after you have at least some
familiarity with the programming language.
Also, please see the Posting Guidelines that are posted here frequently.
I am trying to write a script that will read
records and print the total number of people registered for each
seminar.
use CGI qw(:standard -debug);
There is no point in including a module if you are not going
to make use of any of its features.
use strict;
You should always enable warnings when developing Perl code:
use warnings;
#declare variables
my ($name, $seminar, @records, %sem_count);
You should declare each variable at its first use, rather
than all at the top.
my @name_count = (0);
Why is this an array?
my %sem_count = ("Computer Maintenance", 0,
"Microsoft Office", 0,
"Unix Essentials", 0,
"CGI/Perl", 0);
#calculate people registered and seminar count
open(INFILE, "<", "list.txt")
or die "Error opening list.txt. $!, stopped";
my @records = <INFILE>;
close(INFILE);
foreach my $rec (@records) {
chomp($rec);
Reading them all into an array only to process them one-at-a-time
anyway is silly.
If you are going to process them one-at-a-time, then simply
read them one at a time.
while (my $rec = <INFILE> ) {
($name, $seminar) = split(/,/ , $rec);
$name_count [$name] = $name_count[$name] + 1;
You should always enable warnings when developing Perl code.
It would have pointed out what your problem is.
What is in $name? A string.
You are using a string as an array index, so the string
will be converted to a number to use for indexing the array.
All of your strings will evaluate to zero when you use them
where Perl was expecting a number (like in an array index).
So, you keep adding things to $array[0], and never have
any other elements in the array.
Why? A scalar can hold a number (count) just fine, you don't
need an array for that.
$sem_count {$seminar} = $sem_count{$seminar} +1;
What is in $seminar? A number.
So, the hash keys here will all be numbers, while you earlier
put 4 _string_ keys in there.
You should print out your intermediate data structures when
debugging to see if they contain what you think they contain:
print "$_ ==> $sem_count{$_}\n" for sort keys %sem_count;
}
#generate HTML
If you are not having a problem printing the HTML, then we don't
need to see the printing of the HTML.
foreach my $key ("Computer Maintenance", "Microsoft Office", "Unix
Essentials", "CGI/Perl") {
You only examine the stringy keys, you never look a the numbery keys.
print "<tr><td>$key</td> <td>$sem_count{$key}</td></tr>\n";
}
What I haven't figured out how
to do is total the second field to get the number attending each
seminar. The numbers represent which seminar by 1-Computer Maintenance,
2-Microsoft Office, 3-Unix Essentials, and 4-CGI/Perl. I keep coming up
with 0 for each event.
That is because you are adding to $sem_count{1} instead of
to $sem_count{'Computer Maintenance'} when counting.
---------------------------------
#!/usr/bin/perl
use warnings;
use strict;
my %course_codes = ( 1 => 'Computer Maintenance',
2 => 'Microsoft Office',
3 => 'Unix Essentials',
4 => 'CGI/Perl'
);
my $name_count;
my %sem_count;
while ( my $rec = <DATA> ) {
chomp($rec);
my($name, $sem_num) = split(/,/ , $rec);
$name_count++;
$sem_count{ $course_codes{$sem_num} }++;
}
foreach my $key ("Computer Maintenance", "Microsoft Office",
"Unix Essentials", "CGI/Perl") {
print "$key ==> $sem_count{$key}\n";
}
print "Total registered: $name_count\n";
__DATA__
Janice Alto,3
Nancy Perez,1
James Houza,2
Beth Jimminez,2
Michael Hiller,4
Inez Smith,4
Paul Eniudo,3
Tess Bacza,2
Robert Hau,1
Opal Jones,2
---------------------------------
Thanks for any ideas you may have.
Indent your code to help show the structure of your program.
Get your program working from the command line before moving
it to a CGI environment for further testing.
--
Tad McClellan SGML consulting
tadmc@xxxxxxxxxxxxxx Perl programming
Fort Worth, Texas
.
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