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reverse data read.

Posted on 1998-11-11
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Last Modified: 2010-03-04
Basically I am reading data in from a flat-file that looks like this:  (format like $itemid|$reportdate|)

0|10/1/1998|
1|11/08/1998|
2|11/10/1998|
3|11/25/1998|
4|12/01/1998|
5|12/05/1998|
6|12/6/1998|
7|1111|

using code like this:

open(adb,$resourcedb);
while (<adb>) {
open (AFILE,"$resourcedb") || die "Content-type: text/html\n\nCan't Open $resourcedb(r): $!\n";
@LINES=<AFILE>;
close(AFILE);
$SIZE=@LINES;
for ($i=0;$i<=$SIZE;$i++) {
   $_=$LINES[$i];
($itemid, $reportdate) = split(/\|/,$_);
print "<A HREF=\"reports/$itemid\">$reportdate\</A><BR>\n";
}
close(adb);
}


BUT - I don't want to read/print from top down, I would prefer it be in reverse order i.e. reading/printing the last record (record 7) first then going back to record 0 - any easy way to do this off the top of your head?

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Question by:asago
2 Comments
 
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Accepted Solution

by:
b2pi earned 400 total points
ID: 1206151
Well, you could do:

for ($i = $SIZE; $i >= 0; $i--)

Or, you could do

@LINES = reverse(@LINES)

But you really better hope that @LINES is relatively small.  This could get ugly (as could the @LINES = <AFILE> ) as the size of the array in memory approaches the size of your physical memory.
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LVL 85

Expert Comment

by:ozo
ID: 1206152
for( reverse <AFILE> ){
  ($itemid, $reportdate) = split/\|/;
   print qq?<A HREF="reports/$itemid">$reportdate</A><BR>\n?;
}

#but why are you doing this looping over each line of <adb>?
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