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read fields from the textfile without using any loop

Sushma
Novice

Jan 19, 2012, 2:11 AM

Post #1 of 10 (1783 views)

read fields from the textfile without using any loop	Can't Post

Hi,

i m trying to read the 4th field of each line of a text file without using any loop. is it possible in perl? can anybody help me?

Thanks,

Sushma.

rovf
Veteran

Jan 19, 2012, 5:49 AM

Post #2 of 10 (1777 views)

Re: [Sushma] read fields from the textfile without using any loop [In reply to]	Can't Post

This depends on how you define the word "loop", but maybe the functions map and split will do what you want.

Sushma
Novice

Jan 19, 2012, 5:54 AM

Post #3 of 10 (1776 views)

Re: [rovf] read fields from the textfile without using any loop [In reply to]	Can't Post

split ll work for only one line not for all the line. i tried using split also.

Thanks,

Sushma.

rovf
Veteran

Jan 19, 2012, 6:22 AM

Post #4 of 10 (1775 views)

Re: [Sushma] read fields from the textfile without using any loop [In reply to]	Can't Post

Please read my reply again, and pay attention to the two words before the word "split".

FishMonger
Veteran

Jan 19, 2012, 9:10 AM

Post #5 of 10 (1766 views)

Re: [Sushma] read fields from the textfile without using any loop [In reply to]	Can't Post

Why don't you want to use a loop?

Here's an equally logical question to yours.

How can I drive my car to the store without driving on any roads?

(This post was edited by FishMonger on Jan 19, 2012, 9:12 AM)

rovf
Veteran

Jan 20, 2012, 2:17 AM

Post #6 of 10 (1711 views)

Re: [FishMonger] read fields from the textfile without using any loop [In reply to]	Can't Post

Quote

How can I drive my car to the store without driving on any roads?

I guess there are quite a few SUV addicts who would find this question completely reasonable ;-)

And of course, seeing programming as a sportive activity, we programmers know perfectly well: It is possible to enter any garden without using the garden door, and it is possible to write any program using only recursive functions and "if" (but no "else" please - "else" branches are for sissies).

FishMonger
Veteran

Jan 20, 2012, 6:20 AM

Post #7 of 10 (1703 views)

Re: [rovf] read fields from the textfile without using any loop [In reply to]	Can't Post

In Reply To

I guess there are quite a few SUV addicts who would find this question completely reasonable ;-)

I thought of that when I was posting, but since we programmers need to be picky and pay attention to minuet details, SUV's aren't cars. They are automobiles. :)

In Reply To

And of course, seeing programming as a sportive activity, we programmers know perfectly well: It is possible to enter any garden without using the garden door, and it is possible to write any program using only recursive functions and "if" (but no "else" please - "else" branches are for sissies).

And by god, NO elsif :-)

BillKSmith
Veteran

Jan 20, 2012, 11:01 AM

Post #8 of 10 (1690 views)

Re: [FishMonger] read fields from the textfile without using any loop [In reply to]	Can't Post

Sometimes it is fun to drive off-road.

Code

  
 
use strict; 
use warnings; 
$/ = undef; 
my $file_content = <DATA>; 
my $FIELD = qr/[^,]*/; 
my @fours = $file_content =~ /^(?:$FIELD,){3}($FIELD)/msg; 
print join( "\n", @fours), "\n"; 
__DATA__ 
1,2,3,4,5,6 
a,b,c,d,e,f 
one,two,three,four,five,six

Good Luck,
Bill

histrung
Novice

Jan 22, 2012, 11:38 AM

Post #9 of 10 (1645 views)

Re: [BillKSmith] read fields from the textfile without using any loop [In reply to]	Can't Post

Can you explain the use of ?:, I read the perl docs but not sinking in.

BillKSmith
Veteran

Jan 22, 2012, 5:08 PM

Post #10 of 10 (1627 views)

Re: [histrung] read fields from the textfile without using any loop [In reply to]	Can't Post

This is part of the syntax for "non-capturing parenthesis" I need parenthesis to make {3} refer to the right things, but did not want their contents in the results. Refer: (?:pattern) in perldoc perlre.
Good Luck,
Bill

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