perl newbie File manipulation

[martialartsdrum]

Hi All,
I am a relative newbie to perl and running into a syntax issue.

I need to open a file, search for a certain flag, then extract and manipulate data until another flag is reached.

pseudo code:

open file
while not EOF
read line
if line contains search_flag
while line does not contain end_flag
manipulate data

What I am running into, is that the perl code loops in the while loop waiting for the end_flag and it is never reached because we are not reading from the file from within the loop.

$file = $ARGV[0]; # Name the file
open(INPUTFILE, $file) || die "couldn't open the file!";
@lines = <INPUTFILE>;
foreach (@lines)
{
my($line) = $_;
chomp($line);
if ($line =~ /Processing table/)
{
while ($line !~ /99: VolumeTable/)
{
# here is where I need to manipulate the data
# and increment line.
}
}
}

SO.. the quesion is. How is this accomplished?

thanks

John

 

[feherke]

Hi

While you already slurped in the entire file, I would use [tt]grep[/tt] :

[navy]@lines[/navy] [teal]=[/teal] [green][i]<DATA>[/i][/green][teal];[/teal]
[b]print[/b] [b]grep[/b] [teal]{[/teal] [green][i]/start/../end/[/i][/green] [teal]}[/teal] [navy]@lines[/navy][teal];[/teal]

__DATA__
one
two
three start
four
five
six
seven end
eight
nine
ten

If you prefer the loop, better use a single one and a flag variable :

[b]my[/b] [navy]@lines[/navy] [teal]=[/teal] [green][i]<DATA>[/i][/green][teal];[/teal]
[b]chomp[/b] [navy]@lines[/navy][teal];[/teal]
[b]foreach[/b] [b]my[/b] [navy]$line[/navy] [teal]([/teal][navy]@lines[/navy][teal])[/teal] [teal]{[/teal]
  [navy]$inside[/navy] [teal]=[/teal] [purple]1[/purple] [b]if[/b] [navy]$line[/navy] [teal]=~[/teal] [b]m[/b][fuchsia]/start/[/fuchsia][teal];[/teal]
  [b]if[/b] [teal]([/teal][navy]$inside[/navy][teal])[/teal] [teal]{[/teal]
[gray]#   here is where I need to manipulate the data[/gray]
    [b]print[/b] [green][i]"$line\n"[/i][/green][teal];[/teal]
  [teal]}[/teal]
  [navy]$inside[/navy] [teal]=[/teal] [purple]0[/purple] [b]if[/b] [navy]$line[/navy] [teal]=~[/teal] [b]m[/b][fuchsia]/end/[/fuchsia][teal];[/teal]
[teal]}[/teal]

If you reverse the statements setting the flag, you will get only the inner lines, without the delimiting lines :

[b]my[/b] [navy]@lines[/navy] [teal]=[/teal] [green][i]<data>[/i][/green][teal];[/teal]
[b]chomp[/b] [navy]@lines[/navy][teal];[/teal]
[b]foreach[/b] [b]my[/b] [navy]$line[/navy] [teal]([/teal][navy]@lines[/navy][teal])[/teal] [teal]{[/teal]
  [navy]$inside[/navy] [teal]=[/teal] [purple]0[/purple] [b]if[/b] [navy]$line[/navy] [teal]=~[/teal] [b]m[/b][fuchsia]/end/[/fuchsia][teal];[/teal]
  [b]if[/b] [teal]([/teal][navy]$inside[/navy][teal])[/teal] [teal]{[/teal]
[gray]#   here is where i need to manipulate the data[/gray]
    [b]print[/b] [green][i]"$line\n"[/i][/green][teal];[/teal]
  [teal]}[/teal]
  [navy]$inside[/navy] [teal]=[/teal] [purple]1[/purple] [b]if[/b] [navy]$line[/navy] [teal]=~[/teal] [b]m[/b][fuchsia]/start/[/fuchsia][teal];[/teal]
[teal]}[/teal]

If you want two loops, then you will have to change to two [tt]for[/tt]s and use a common loop control variable :

[b]my[/b] [navy]@lines[/navy] [teal]=[/teal] [green][i]<DATA>[/i][/green][teal];[/teal]
[b]chomp[/b] [navy]@lines[/navy][teal];[/teal]
[b]for[/b] [teal]([/teal][b]my[/b] [navy]$i[/navy][teal]=[/teal][purple]0[/purple][teal],[/teal] [navy]$l[/navy][teal]=[/teal]scalar [navy]@lines[/navy][teal];[/teal] [navy]$i[/navy][teal]<[/teal][navy]$l[/navy][teal];[/teal] [navy]$i[/navy][teal]++)[/teal] [teal]{[/teal]
  [b]if[/b] [teal]([/teal][navy]$lines[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal] [teal]=~[/teal] [b]m[/b][fuchsia]/start/[/fuchsia][teal])[/teal] [teal]{[/teal]
    [b]for[/b] [teal](;[/teal] [navy]$i[/navy][teal]<[/teal][navy]$l[/navy][teal];[/teal] [navy]$i[/navy][teal]++)[/teal] [teal]{[/teal]
[gray]#     here is where I need to manipulate the data[/gray]
      [b]print[/b] [green][i]"$lines[$i]\n"[/i][/green][teal];[/teal]
      [b]last[/b] [b]if[/b] [navy]$lines[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal] [teal]=~[/teal] [b]m[/b][fuchsia]/end/[/fuchsia][teal];[/teal]
    [teal]}[/teal]
  [teal]}[/teal]
[teal]}[/teal]

Feherke.

 

[prex1]

This is how I would do that:

$file = $ARGV[0];
open(INPUTFILE,$file)||die"couldn't open the file!";
while(<INPUTFILE>){
  last if/Processing table/;
}
while(<INPUTFILE>){
  last if/99: VolumeTable/;
#          manipulate the data 
}

Franco

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