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I am reading each record from an input text file using the foreach
loop. Once my search of a pattern in a record is true - i want to skip
next n lines.

How do i get this done,

TIA,

Sanju

wrote:

> I am reading each record from an input text file using the foreach
> loop.

Really? Why? That's rather unnatural. Can you show us what you mean
(please see posting guidelines).

> Once my search of a pattern in a record is true - i want to skip
> next n lines.
>
> How do i get this done,

In general the way to have a foreach skip is something like...

my $skip;
foreach ( whatever ) {
if ($skip) { $skip--; next }
if ( some_condition ) {
$skip = 5;
}
}

But if you took the conventional approach of reading the file a line at
a time in a while loop is would be simpler. Then you could just read
and discard some lines.

local *_;
while ( <$filehandle> ) {
if ( some_condition ) {
<$filehandle> for 1 .. 5;
}
}

wrote:
> I am reading each record from an input text file using the foreach
> loop. Once my search of a pattern in a record is true - i want to skip
> next n lines.
>
> How do i get this done,

TIMTOWTDI, but my initial instinct is to use the "flip-flop" operator
(which is the .. operator used in scalar context). Read more about it
in
perldoc perlop

This program sets the number of lines to skip when a number is found.
When a number is found, that many lines are skipped. All others are
printed.

Paul Lalli

#!/usr/bin/perl
use strict;
use warnings;
#when find a number, skip the next five lines

my $skips = 4;
while (<DATA>){

next if (/\d/ .. !$skips--);
print;
$skips = 4;
}


__DATA__
one
two
three
Here's the 4th!
five
six
seven
eight
nine
ten
eleven
Another number: 12
thirteen
fourteen
fifteen
sixteen
seventeen
eightteen
nineteen

<> wrote:

> I am reading each record from an input text file using the foreach
> loop.


A foreach reads ALL of the lines into memory at once.

You should probably be using a while loop instead.


> Once my search of a pattern in a record is true - i want to skip
> next n lines.
>
> How do i get this done,


my $n = 5; # untested
while ( <DATA> ) {
if ( /some pattern/ ) {
scalar(<DATA>) for 1 .. $n;
}
}


--
Tad McClellan SGML consulting
Perl programming
Fort Worth, Texas

wrote:
> I am reading each record from an input text file using the foreach
> loop. Once my search of a pattern in a record is true - i want to skip
> next n lines.
>
> How do i get this done,
>
> TIA,
>
> Sanju
>

As with a previous post, I would rather use a while loop:

1 #!/usr/bin/perl
2
3 use strict;
4
5 my $skipcount = 0;
6 my $skipset = 0;
7
8 while(<>){
9
10 chomp;
11 if( $skipset ){
12
13 $skipcount++;
14 if( $skipset == $skipcount ) {
15
16 $skipset = 0;
17 $skipcount = 0;
18
19 }
20
21 } else {
22
23 if( /^skip\s+(\d+)/i ) {
24
25 $skipset = $1;
26
27 } else {
28
29 print "Reading line: $_\n";
30
31 }
32
33 }
34
35 }
36

with the file saved as process.pl and the data file called 'file', I get
the following output:

$ cat file | ./process.pl
Reading line: read 1
Reading line: read 2
Reading line: read 3
Reading line: read 4
Reading line: read 5
Reading line: read 6
Reading line: read 7
Reading line: read 11
Reading line: read 12
Reading line: read 15
Reading line: read 16
Reading line: read 17
Reading line: read 18

$ cat file
read 1
read 2
read 3
read 4
read 5
read 6
read 7
skip 3
read 8
read 9
read 10
read 11
read 12
skip 2
read 13
read 14
read 15
read 16
read 17
read 18




Hope that helps

Cheers

Nico

wrote:
> I am reading each record from an input text file using the foreach
> loop. Once my search of a pattern in a record is true - i want to skip
> next n lines.
>
> How do i get this done,
>
> TIA,
>
> Sanju
>

As with a previous post, I would rather use a while loop:

1 #!/usr/bin/perl
2
3 use strict;
4
5 my $skipcount = 0;
6 my $skipset = 0;
7
8 while(<>){
9
10 chomp;
11 if( $skipset ){
12
13 $skipcount++;
14 if( $skipset == $skipcount ) {
15
16 $skipset = 0;
17 $skipcount = 0;
18
19 }
20
21 } else {
22
23 if( /^skip\s+(\d+)/i ) {
24
25 $skipset = $1;
26
27 } else {
28
29 print "Reading line: $_\n";
30
31 }
32
33 }
34
35 }
36

with the file saved as process.pl and the data file called 'file', I get
the following output:

$ cat file | ./process.pl
Reading line: read 1
Reading line: read 2
Reading line: read 3
Reading line: read 4
Reading line: read 5
Reading line: read 6
Reading line: read 7
Reading line: read 11
Reading line: read 12
Reading line: read 15
Reading line: read 16
Reading line: read 17
Reading line: read 18

$ cat file
read 1
read 2
read 3
read 4
read 5
read 6
read 7
skip 3
read 8
read 9
read 10
read 11
read 12
skip 2
read 13
read 14
read 15
read 16
read 17
read 18




Hope that helps

Cheers

Nico