http://www.perlmonks.org?node_id=990965

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

hi perl monks!,....

please help me whether i am on the right track

i have an issue in handling line contiuation..

my line 1 is said to be continued to line 2 only when my 72nd column has '*'.

Things i am trying to do is

1) check whether 72nd column is *

2)chomp the newline character...

here, this situation occurs at any line in the code. and i want to retain the rest of the code as it is.

can anyone suggest me a better method?...

Thanks in advance...

Replies are listed 'Best First'.
Re: how to append 2 lines
by aitap (Curate) on Aug 31, 2012 at 10:10 UTC
[reply]

      Hi,here is the sample input code... 

      LABEL#00001
         
         MVC   SYMBOL+2(4),X.PDES_KEY+2                               
+          
         MVC   SYMB_ART,=C'XSEQ'              //line comments         
+                         
                                                                      
+          
         F$SFH SELECT,LISTING,                                        
+ *        
               DESKART=SYMB_ART,                                      
+ *        
               DESKWERT=SYMBOL,                                       
+ *        
               MARKTCODE=L#MACF                                       
+          
         BNE   F03#000                     //line comments

      [download]

      my required output should be somewhat like this... 

      LABEL#00001
         
         MVC   SYMBOL+2(4),X.PDES_KEY+2                               
+          
         MVC   SYMB_ART,=C'XSEQ'              //line comments         
+                         
                                                                      
+          
         F$SFH SELECT,LISTING,DESKART=SYMB_ART,DESKWERT=SYMBOL,MARKTCO
+DE=L#MACF                                                 
         BNE   F03#000                     //line comments

      [download]
[reply]
[d/l]
[select]

        And your Perl code to join the lines is...

        Hint: use three-argument form of substr to check the 72nd symbol of the line and use it again to replace the text. For example: 

        my $one = ("_"x9)."*__\n";
my $two = ("-"x15)."\n";
print "$one$two";
substr($one,9)="" if substr($one,9,1) eq "*";
print "$one$two";

        [download]

        Sorry if my advice was wrong.
[reply]
[d/l]
        Ok, but that is only DATA, that is not perl
[reply]
Re: how to append 2 lines
by philiprbrenan (Monk) on Sep 01, 2012 at 17:23 UTC

    Something along the lines of:

    use feature ":5.14";
use warnings FATAL => qw(all);
use strict;

my ($c, $s) = (0, '');
for(split /\n/, << 'END') 
LABEL#00001
         
         MVC   SYMBOL+2(4),X.PDES_KEY+2                               
+          
         MVC   SYMB_ART,=C'XSEQ'              //line comments         
+                         
                                                                      
+          
         F$SFH SELECT,LISTING,                                        
+ *        
               DESKART=SYMB_ART,                                      
+ *        
               DESKWERT=SYMBOL,                                       
+ *        
               MARKTCODE=L#MACF                                       
+          
         BNE   F03#000                     //line comments
END

 {if (length > 71 and substr($_, 71, 1) eq '*') # Detect continuation
   {s/\A\s*// if $c == 1;                       # Strip leading space 
+in continuation  
    s/\s*\*\s*\Z//;                             # Strip trailing space
    ($s, $c) = (($c ? $s : '').$_, 1);          # Concatenate or resta
+rt depending on continuation state
   }
  else
   {s/\A\s*// if $c == 1;                       # Strip leading spaces
+ in continuation
    say "$s$_";                                 # Write completed stat
+ement
    ($s, $c) = ('', 0);                         # Restart
   }
 }

    [download]

    Produces

    LABEL#00001
         
         MVC   SYMBOL+2(4),X.PDES_KEY+2                               
+          
         MVC   SYMB_ART,=C'XSEQ'              //line comments         
+                         
                                                                      
+          
         F$SFH SELECT,LISTING,DESKART=SYMB_ART,DESKWERT=SYMBOL,MARKTCO
+DE=L#MACF                                                 
         BNE   F03#000                     //line comments

    [download]
[reply]
[d/l]
[select]
      Hi,....

      Thanks for the advice....

      but another doubt....This is fine if i give the input then and there... but i want to give my input in a file... i want to perform this action for the above lines in a file.. please help me in this also...

      Thanks in advance...

[reply]

        May I suggest something like this to read your lines of text: 

        use feature ":5.14";
use warnings FATAL => qw(all);
use strict;
use Data::Dump qw(dump pp);

sub readFile($)
 {my ($f) = @_;
  $f or die "readFile: No file specified";
  open my $F, "<$f" or die "Cannot open $f for input";
  local $/ = undef;
  <$F> 
 }

print readFile("readFile.pm");

        [download]

        Produces:

        use feature ":5.14";
use warnings FATAL => qw(all);
use strict;
use Data::Dump qw(dump pp);

sub readFile($)
 {my ($f) = @_;
  $f or die "readFile: No file specified";
  open my $F, "<$f" or die "Cannot open $f for input";
  local $/ = undef;
  <$F> 
 }

print readFile("readFile.pm");

        [download]
[reply]
[d/l]
[select]

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