in reply to Extract the variable

I'm guessing you're trying to use $var. You could either not use s///:

$var =~ /^\.\w+\s+(\w+)\s+./;
$var = $1;

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or finish off what you had there:

$var =~ s/^(\.\w+\s+)(\w+)(\s+.+)/$2/;

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(note the + near the end, which allows more than one character to match; the result of the substitution in $var is what's left over after you did the substituting)

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Re^2: Extract the variable
by denzil_cactus (Sexton) on Jun 25, 2007 at 12:25 UTC
    Now my file contains these data 
    .rem *****************************************************************
+*****
.rem *                                                                
+    *
.rem *                           deb123.rpt                           
+    *
.rem *****************************************************************
+*****
.rem
.rem ------------------------ book_tab variables ---------------------
.rem
.declare book_no                     a14
.declare l_code                      a10
.declare l_book                         a12
.declare book_date                     a13

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    and I need to read this file line by line the file name is deb123.rpt and my code is 
    use IO::File;



my $fh = IO::File->new();





die "File $ARGV[0] is there in the specified location but is of Zero b
+ytes"  if (-z $ARGV[0]);
$ARGV[0] .= ".rpt";

$fh->open($ARGV[0], "r");
local($/);
#my $data = $fh->getline;
#$fh->close;
while(defined($data = $fh->getline)){



if($data =~ /^\.r/){

print "This is a comment $data\n";

}
if($data =~ /^\.dec/){

print "This is declared variable $data\n";
}



}
$fh->close;

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    but its not giving any output and even its not printing the data at particular line in the file also... Please help me out for the code
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[d/l]
[select]
      Your use of my leads me to hope that you are putting use strict; and use warnings; at the top of your scripts. It is also a good idea to indent your code (my preference is four spaces) to give a visual indication to control flow.

      I'm not sure why you are using IO::File when three-argument open anf lexical filehandle will serve as well. I have used your data but have added a bogus line to demonstrate how to handle lines that don't fit your expectations. I use a regex capture to get the variable name (captured in $1) and print it out; obviously, you can assign it to a variable for later use. Once you know what a line is and have dealt with it, use next to get the next line rather than testing further. Here is the input file

      Read more... (1032 Bytes)

      the code

      use strict;
use warnings;

my $inFile = q{spw623147.txt};
open my $inFH, q{<}, $inFile
   or die qq{open: $inFile: $!\n};

while ( <$inFH> )
{
    if ( m{\A\.rem} )
    {
        print qq{  Comment Line: $_};
        next;
    }
    if ( m{\A\.declare\s+(\S+)} )
    {
        print qq{     Data Line: $_};
        print qq{   Variable is: $1\n};
        next;
    }
    print qq{Not recognised: $_};
}

close $inFH
   or die qq{close: $inFile: $!\n};

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      and the output

        Comment Line: .rem *************************************************
+*********************
  Comment Line: .rem *                                                
+                    *
  Comment Line: .rem *                           deb123.rpt           
+                    *
  Comment Line: .rem *************************************************
+*********************
  Comment Line: .rem
  Comment Line: .rem ------------------------ book_tab variables -----
+----------------
  Comment Line: .rem
     Data Line: .declare book_no                     a14
   Variable is: book_no
     Data Line: .declare l_code                      a10
   Variable is: l_code
Not recognised: .burble nonsense directive here
     Data Line: .declare l_book                         a12
   Variable is: l_book
     Data Line: .declare book_date                     a13
   Variable is: book_date

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      I hope thisis of use.

      Cheers,

      JohnGG

      Update: Fixed typo

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[d/l]
[select]
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Re^2: Extract the variable
by blazar (Canon) on Jun 26, 2007 at 08:53 UTC 
    $var =~ /^\.\w+\s+(\w+)\s+./;
$var = $1;

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    While this is the obvious and most reasonable suggestion, given the apparent level of (in-)expertise of the OP, it should be worth reminding him of always checking whether the match actually succeeded.

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[d/l]
Re^2: Extract the variable
by denzil_cactus (Sexton) on Jun 25, 2007 at 12:07 UTC
    Thanx dear!!! Its working now!!! Can I use substr instead of regex?
[reply]
      &ot

      Presuming ".declare " is a fixed prefix and the variable name is always followed by a real space character (i.e. you're not worried that there's a TAB instead) then yes you could use substr starting at offset 10 after using index (also starting at offset 10) to find where the variable name ends.

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