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Subject Author Date
looping issue dakin999 06-30-2008
|--> Re: looping issue Gunnar Hjalmars...06-30-2008
| `--> Re: looping issue Tad J McClellan06-30-2008
Posted by dakin999 on June 30, 2008, 3:45 am
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 Hi, I have following code:

foreach my $row (@$array_ref) {
my ( $usr, $usr_det, $pwd_val) = @$row;
#print "\tuser id :$usr\n";
#print "\tcard no :$usr_det\n";
#print "\tpasswd :$pwd_val\n";
open (FILE, "<file_name") || die "Could not open the file: $!";
while (<FILE>) {
chomp;
(my $nusr_id) = split(); #read into a variable
--
--
--
}
}

The problem is in the looping of input <FILE> that I need to read for
each $row. Basically there can be more than 1 $row values and I need
to pick a new line from <FILE> for each $row entry.

Any suggestions for doing this??

Posted by Gunnar Hjalmarsson on June 30, 2008, 4:46 am
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 dakin999 wrote:
> Hi, I have following code:
>
> foreach my $row (@$array_ref) {
> my ( $usr, $usr_det, $pwd_val) = @$row;
> #print "\tuser id :$usr\n";
> #print "\tcard no :$usr_det\n";
> #print "\tpasswd :$pwd_val\n";
> open (FILE, "<file_name") || die "Could not open the file: $!";
> while (<FILE>) {
> chomp;
> (my $nusr_id) = split(); #read into a variable
> --
> --
> --
> }
> }
>
> The problem is in the looping of input <FILE> that I need to read for
> each $row. Basically there can be more than 1 $row values and I need
> to pick a new line from <FILE> for each $row entry.
>
> Any suggestions for doing this??

Please clarify what "this" means.

Possibly you mean that you want to look up a value in "file_name" for
each $row. That would indicate that you ought to store the file data in
a hash variable.

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl

Posted by rthangam on June 30, 2008, 5:07 am
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> Hi, I have following code:
>
> foreach my $row (@$array_ref) {
> my ( $usr, $usr_det, $pwd_val) = @$row;
> #print "\tuser id :$usr\n";
> #print "\tcard no :$usr_det\n";
> #print "\tpasswd :$pwd_val\n";
> open (FILE, "<file_name") || die "Could not open the file: $!";
> while (<FILE>) {
> chomp;
> (my $nusr_id) = split(); #read into a variable
> --
> --
> --
> }
> }
>
> The problem is in the looping of input <FILE> that I need to read for
> each $row. Basically there can be more than 1 $row values and I need
> to pick a new line from <FILE> for each $row entry.
>
> Any suggestions for doing this??

You can do it this way. Open the file before the for ... loop and use
readline() function which accepts the filehandle as parameter to get a
line at a time. For eg.,

open(FH,"test.txt") or die $!;
my $line = readline(FH);
print $line;

$line = readline(FH);
print $line;

You can also try some other modules like FileHandle which is object
oriented and also has methods like getline(), getlines() etc.

Posted by Tad J McClellan on June 30, 2008, 7:49 am
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> my $line = readline(FH);


Or use the more common equivalent:

my $line = <FH>;


--
Tad McClellan
email: perl -le "print scalar reverse qq/moc.noitatibaher0cmdat/"

Posted by Jürgen Exner on June 30, 2008, 7:38 am
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> foreach my $row (@$array_ref) {
[...]
> open (FILE, "<file_name") || die "Could not open the file: $!";
> while (<FILE>) {
> chomp;
> (my $nusr_id) = split(); #read into a variable
> --
> --
> --
> }
> }

This code reads and loops through all of <FILE> for each element of
@$array_ref.

> The problem is in the looping of input <FILE> that I need to read for
>each $row. Basically there can be more than 1 $row values and I need
>to pick a new line from <FILE> for each $row entry.

Are you saying that is not what you want but instead you want to loop
through @$array_ref and <FILE> in sync, i.e. for each element of
@$array_ref read exactly one line of <FILE>?
If so, then just do it:

open (FILE, "<file_name") || die "Could not open the file: $!";
foreach my $row (@$array_ref) {
[...]
        $_ = <FILE>;
        chomp;
        (my $nusr_id) = split(); #read into a variable
         --
         --
         --
}

jue

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