David Gilden wrote:
> Good morning,
Hello,
> I would like to populate a hash from a csv text file,
Do you really think that you need to?
> then test for the existence of a value in the hash.
A value? Or a key?
perldoc -f exists
> If not found return an error message and exit.
>
>
> ithe text file will have the format of:
> # whitelist created 2/18/06 or some other comment on the first line
> name1,nick1
> ---
> name25,nick25
> ---
>
> my $approvedUser = pram('approvedUser'); # cgi.pm
>
> my $whitelist = './'whitelist.txt;
That is a syntax error, perhaps you meant:
my $whitelist = './whitelist.txt';
> my %hash
>
> open(EL,"$whitelist") || &errorMessage( "Read in, Could not find $whitelist,
> $!");
perldoc -q quoting
You are using an ampersand on the subroutine which has certain side-effects
that may not be desirable.
perldoc perlsub
> my @lines = <EL>;
You are reading the whole file into memory but that is not really nessesary.
> close(EL);
>
> foreach(@lines){
> next if /#/;
> my($key,$val)= split (@lines,",");
perldoc -f split
split /PATTERN/,EXPR,LIMIT
split() uses the first argument as a regular expression pattern so assuming
@lines has 23 elements in it, it will be converted to the number 23 and that
will be used as the pattern to split on:
my($key,$val)= split (/23/,",");
Since the string "," has no '23' (or any digits at all) in it, it will be
returned unaltered and assigned to the $key variable.
> $hash{$key} = $val;
> }
> close(EL);
>
> if (!defined $approvedUser =~ %hash){
The expression to the right of the binding operator (=~) will be treated as a
regular expression pattern and a hash in scalar context evaluates to a number
so your expression is something like:
if ( !defined $approvedUser =~ m-5/8- ){
The match operator will never return an undefined value so your error message
will never print.
> &errorMessage( "your not an authorized user")
> }
>
>
> errorMessage(message){
perldoc perlsub
If you want to define a subroutine you have to use:
sub errorMessage {
> shift;
shift() removes the first element of an array and returns it. Inside a
subroutine, if you don't specify an array it defaults to the @_ array which
contains all the values passed to the subroutine. You are not assigning the
return value of shift() to a variable so it disappears.
> print "$_\n";
You have not assigned a value to $_ so nothing (except a newline) will be
printed.
> exit;
You should usually exit() with a value that signifies success or failure.
Most OSs use zero for success and a non-zero value for failure.
> }
>
>
> How close am I to having a working script, I have guessed at some of syntax
> here, and am not familiar
> with using 'defined'.
If you just want to see if a certain name is present in the file you can do
something like this:
use warnings;
use strict;
sub errorMessage {
my $message = shift;
print "$message\n";
exit 1;
}
my $approvedUser = param( 'approvedUser' ); # cgi.pm
my $whitelist = 'whitelist.txt';
open EL, '<', $whitelist
or errorMessage( "Read in, Could not open $whitelist, $!");
my ( $key, $val );
while ( <EL> ) {
next if /#/;
( $key, $val ) = /^([^,]+),(.+)/;
last if $approvedUser eq $key;
}
errorMessage( 'you are not an authorized user' )
unless defined $key;
__END__
If you do really need a hash then:
use warnings;
use strict;
sub errorMessage {
my $message = shift;
print "$message\n";
exit 1;
}
my $approvedUser = param( 'approvedUser' ); # cgi.pm
my $whitelist = 'whitelist.txt';
open EL, '<', $whitelist
or errorMessage( "Read in, Could not open $whitelist, $!");
my %hash;
while ( <EL> ) {
next if /#/;
my ( $key, $val ) = /^([^,]+),(.+)/;
$hash{ $key } = $val;
}
errorMessage( 'you are not an authorized user' )
unless exists $hash{ $approvedUser };
__END__
John
--
use Perl;
program
fulfillment
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