Mosley has asked for the wisdom of the Perl Monks concerning the following question:

I have a database of lines separated by |. I have been opening my database and putting all lines in an @array then spliting them with a for each loop, then printing them. I now want to extract only a hundred lines and split them. But I need to start at a certian line number, for example read lines 1-100, 101-200, 201-300 and so on. Put those lines an array I can run a for each loop on and split them. Or maybe someone has a better solution. Please help. Thanks
  • Comment on How do I extract (x) number of lines from database?

Replies are listed 'Best First'.
Re: How do I extract (x) number of lines from database?
by AidanLee (Chaplain) on Sep 21, 2001 at 08:30 UTC

    if you've got them in an array it should be fairly easy to do this using an array slice.

    my @array = <FILE>; #or however you've retrieved your lines

foreach my $line ( @array[99..199] )
{
  #munge line here
}

    [download]

    you can put variables in for the bottom and top of your slice range.

    p.s., you might really want to consider using either a templating system, CGI.pm, or at the very least HEREDOC syntax to deal with all that messy html output.

[reply]
[d/l]
      Thanks Everybody! Peace Out! Mosley
[reply]
Re: How do I extract (x) number of lines from database?
by jlongino (Parson) on Sep 21, 2001 at 07:19 UTC
    You stated that the lines are separated by "|". But the rest of your narrative implies that you meant that the fields of each line are separated by "|". So I am assuming the latter: 
    use strict;

my ($begline, $endline);
open DATA, "<indb.txt";
my @lines = <DATA>;
chomp @lines;

foreach ($begline..$endline) {
   my ($var1, $var2, $var3) = split '\|', $lines[$_];
   print "$var1 $var2 $var3\n";
   # do whatever
}

    [download]
    If this isn't what you meant, please clarify.

    Update: Of course you need to initialize $begline, $endline as needed. Also, keep in mind that @lines begins with an index of zero, not one. 

    @a=split??,'just lose the ego and get involved!';
for(split??,'afqtw{|~'){print $a[ord($_)-97]}
[reply]
[d/l]
      My current code is as follows, if you could show me how to extract lines 10 thru 20, Thanks. 
      $linenum = 1;
$altnum = 1;

open(FILE, "<data/data.txt");
@lines = <FILE>;
close(FILE);

# prints out table header
print "<center><table border=\"0\" cellpadding=\"3\" width=\"596\" bgc
+olor=\"#000080\"><tr><td bgcolor=\"#000050\" colspan=\"2\">Free Host 
+Name<\/font><\/td><td bgcolor=\"#000050\" align=\"center\">Space<\/fo
+nt><\/td><td bgcolor=\"#000050\" align=\"center\">Uploads<\/font><\/t
+d><td bgcolor=\"#000050\" align=\"center\">Forced Ads<\/font><\/td><t
+d bgcolor=\"#000050\" align=\"center\">Scripts<\/font><\/td><td bgcol
+or=\"#000050\" align=\"center\">Features<\/font><\/td><\/tr>\n";

foreach $item (@lines) {

@thisArray = split(/\|/, $item); 

# just alternating td bgcolor with these next two lines
if ($altnum eq "1") { $altnum = 0;  $bgc = "#000080"; } 
elsif ($altnum eq "0") { $altnum = 1;  $bgc = "#000050"; }

print "<tr><td bgcolor=\"#000050\" align=\"center\">@thisArray[0]<\/fo
+nt><\/td><td bgcolor=\"$bgc\"><a href=\"goto.cgi?@thisArray[0]\">@thi
+sArray[1]<\/a><\/font><\/td><td bgcolor=\"$bgc\" align=\"center\">@th
+isArray[6] MB<\/font><\/td><td bgcolor=\"$bgc\">@thisArray[7]<\/font>
+<\/td><td  bgcolor=\"$bgc\" align=\"center\">@thisArray[5]<\/font><\/
+td><td  bgcolor=\"$bgc\" align=\"center\">@thisArray[10]<\/font><\/td
+><td bgcolor=\"#000050\" align=\"center\"><a href=\"more.cgi?@thisArr
+ay[0]\">more<\/font><\/a><\/td><\/tr>";

$linenum++;            
}
print "<\/td><\/tr><\/table>\n\n"; 


___DATA____
1|0 catch|english|personal|http://www.0catch.com|popup|100|ftp browser
+ fp|advanced basic|domainhosting subdomain counter form guestbook|col
+lection|
2|100megsfree|english|personal|http://www.100megsfree.com|banner|100|f
+tp browser email|advanced basic|subdomain messageboard form guestbook
+|collection|
3|10mbfree|english|personal|http://www.10mbfree.com|other|10|browser||
+subdomain messageboard guestbook|collection|
4|15m4u|english|personal business game|http://www.15m4u.cjb.net|no ads
+|15|ftp email||php subdomain ssi cgi-bin|cgi-bin|
5|1hwy|english|personal|http://www.1hwy.com|banner|0|ftp browser|advan
+ced basic|subdomain counter form guestbook|collection|
6|20megsfree.com|english|personal business game|http://www.20megsfree.
+com|banner|20|ftp browser email|advanced basic|pop email subdomain co
+unter form guestbook|collection|
7|20megs|english|personal|http://www.20megs.com/||20|browser|advanced 
+basic|messageboard guestbook|collection|
8|2d adventure|english|game|http://www.2dadventure.com|button|999|brow
+ser|basic||no|
9|30mbfree|english|personal|http://www.30mbfree.com|no ads|0|browser|b
+asic|messageboard form guestbook|collection|
10|321website|english|personal|http://www.321website.com/|adframe|0|br
+owser|advanced|messageboard shopping cart guestbook|collection|
11|3dracing|english|game|http://www.3dracing.com/hosting.htm|banner|20
+|ftp||domainhosting subdomain cgi-bin|cgi-bin|
12|3hosting4u|english|personal business|http://www.3hosting4u.com|no a
+ds|10|browser|advanced basic|counter form guestbook|collection|
13|3megsfree|english|personal|http://www.3megsfree.com|footbanner|0|br
+owser|advanced|counter guestbook|collection|
14|4business|english|business|http://www.4business.net/|banner|20|ftp 
+fp||domainhosting subdomain cgi-bin|cgi-bin|
15|4eit|english|personal business game|http://www.4eit.com|no ads|20|f
+tp email||php realvideo realaudio pop email domainhosting subdomain m
+ysql ssi cgi-bin form guestbook|cgi-bin|
16|4nx2|english|personal business|http://www.4nx2.com|no ads|20|browse
+r|advanced|php mysql|php|
17|4office|english|business|http://www.4office.net/|banner|999|ftp||su
+bdomain cgi-bin|cgi-bin|
18|50megs|english|personal|http://www.50megs.com/|topbanner|50|ftp bro
+wser|advanced basic|domainhosting subdomain messageboard form guestbo
+ok|collection|
19|75megs|english|personal business|http://www.75megs.com/|popup/banne
+r|75|ftp browser|advanced basic|domainhosting subdomain counter form 
+guestbook|collection|
20|800mph|english|personal|http://800mph.com/|adframe|0|browser|advanc
+ed|realvideo realaudio pop email subdomain messageboard counter form 
+guestbook|collection|

      [download]
[reply]
[d/l]
        This is the modified code. Note that I commented out the external file I/O stuff and just used the internal __DATA__ (which incidently should use only two "_"s before and after. you had three). Also, I added "use strict", which you should get into the habit of using, and "my"s where appropriate. Think also about using indentation to make your control structures more readable. 
        use strict;
my $linenum = 1;
my $altnum = 1;
my $bgc;

# open(FILE, "<data/data.txt");
# my @lines = <FILE>;
my @lines = <DATA>;
# close(FILE);

# prints out table header
print "<center><table border=\"0\" cellpadding=\"3\" width=\"596\" bgc
+olor=\"#000080\"><tr><td bgcolor=\"#000050\" colspan=\"2\">Free Host 
+Name<\/font><\/td><td bgcolor=\"#000050\" align=\"center\">Space<\/fo
+nt><\/td><td bgcolor=\"#000050\" align=\"center\">Uploads<\/font><\/t
+d><td bgcolor=\"#000050\" align=\"center\">Forced Ads<\/font><\/td><t
+d bgcolor=\"#000050\" align=\"center\">Scripts<\/font><\/td><td bgcol
+or=\"#000050\" align=\"center\">Features<\/font><\/td><\/tr>\n";     
+   

foreach my $item (@lines[9..19]) {

    my @thisArray = split(/\|/, $item); 

    # just alternating td bgcolor with these next two lines
    if ($altnum eq "1") { 
       $altnum = 0;  
       $bgc = "#000080"; 
    } elsif ($altnum eq "0") {
       $altnum = 1;  
       $bgc = "#000050"; 
    }

    print "<tr><td bgcolor=\"#000050\" align=\"center\">@thisArray[0]<
+\/font><\/td><td bgcolor=\"$bgc\"><a href=\"goto.cgi?@thisArray[0]\">
+@thisArray[1]<\/a><\/font><\/td><td bgcolor=\"$bgc\" align=\"center\"
+>@thisArray[6] MB<\/font><\/td><td bgcolor=\"$bgc\">@thisArray[7]<\/f
+ont><\/td><td  bgcolor=\"$bgc\" align=\"center\">@thisArray[5]<\/font
+><\/td><td  bgcolor=\"$bgc\" align=\"center\">@thisArray[10]<\/font><
+\/td><td bgcolor=\"#000050\" align=\"center\"><a href=\"more.cgi?@thi
+sArray[0]\">more<\/font><\/a><\/td><\/tr>";

    $linenum++;            
}
print "<\/td><\/tr><\/table>\n\n"; 


__DATA__
1|0 catch|english|personal|http://www.0catch.com|popup|100|ftp browser
+ fp|advanced basic|domainhosting subdomain counter form guestbook|col
+lection|
2|100megsfree|english|personal|http://www.100megsfree.com|banner|100|f
+tp browser email|advanced basic|subdomain messageboard form guestbook
+|collection|
3|10mbfree|english|personal|http://www.10mbfree.com|other|10|browser||
+subdomain messageboard guestbook|collection|
4|15m4u|english|personal business game|http://www.15m4u.cjb.net|no ads
+|15|ftp email||php subdomain ssi cgi-bin|cgi-bin|
5|1hwy|english|personal|http://www.1hwy.com|banner|0|ftp browser|advan
+ced basic|subdomain counter form guestbook|collection|
6|20megsfree.com|english|personal business game|http://www.20megsfree.
+com|banner|20|ftp browser email|advanced basic|pop email subdomain co
+unter form guestbook|collection|
7|20megs|english|personal|http://www.20megs.com/||20|browser|advanced 
+basic|messageboard guestbook|collection|
8|2d adventure|english|game|http://www.2dadventure.com|button|999|brow
+ser|basic||no|
9|30mbfree|english|personal|http://www.30mbfree.com|no ads|0|browser|b
+asic|messageboard form guestbook|collection|
10|321website|english|personal|http://www.321website.com/|adframe|0|br
+owser|advanced|messageboard shopping cart guestbook|collection|
11|3dracing|english|game|http://www.3dracing.com/hosting.htm|banner|20
+|ftp||domainhosting subdomain cgi-bin|cgi-bin|
12|3hosting4u|english|personal business|http://www.3hosting4u.com|no a
+ds|10|browser|advanced basic|counter form guestbook|collection|
13|3megsfree|english|personal|http://www.3megsfree.com|footbanner|0|br
+owser|advanced|counter guestbook|collection|
14|4business|english|business|http://www.4business.net/|banner|20|ftp 
+fp||domainhosting subdomain cgi-bin|cgi-bin|
15|4eit|english|personal business game|http://www.4eit.com|no ads|20|f
+tp email||php realvideo realaudio pop email domainhosting subdomain m
+ysql ssi cgi-bin form guestbook|cgi-bin|
16|4nx2|english|personal business|http://www.4nx2.com|no ads|20|browse
+r|advanced|php mysql|php|
17|4office|english|business|http://www.4office.net/|banner|999|ftp||su
+bdomain cgi-bin|cgi-bin|
18|50megs|english|personal|http://www.50megs.com/|topbanner|50|ftp bro
+wser|advanced basic|domainhosting subdomain messageboard form guestbo
+ok|collection|
19|75megs|english|personal business|http://www.75megs.com/|popup/banne
+r|75|ftp browser|advanced basic|domainhosting subdomain counter form 
+guestbook|collection|        +
20|800mph|english|personal|http://800mph.com/|adframe|0|browser|advanc
+ed|realvideo realaudio pop email subdomain messageboard counter form 
+guestbook|collection|

        [download]
        Update: If it wasn't so late, I'd have used a hash with the first field (linenum/ID) as the key field. Maybe a monk in a different timezone could illustrate. As it is, I just fudged the 10-20 with 9-19, which is fine for quick and dirty, but not too aesthetic. 
        @a=split??,'just lose the ego and get involved!';
for(split??,'afqtw{|~'){print $a[ord($_)-97]}
[reply]
[d/l]

Back to Seekers of Perl Wisdom