CODEWITHSUNDEEP
regexperl
akp
akp

Reputation: 13

how to replace every first decimal number of line with binary number w/o effecting other words

I am trying to convert a first decimal word of every line to binary without affecting any other words.

My code is as follows:

use strict;

use warnings;

open (tf, "dec.txt");
open (out1, " > bin.txt");
while (my $line = <tf>){
    my $binary_number = sprintf("%03b", $line); 
    print out1 " $binary_number\n";
}
close (tf);

input file example:

3 4 5 
6 7 2
1 2 3

expected output:

011 4 5
110 7 2
001 2 3

o/p from the code:

011
110
001

Is there any suggestion to achieve o/p file as per expected output? I am missing other words in the line here. those words I want to print as it is.

and also another question: is there a way to read a single column (not line)?

for example in above o/p 1st column ...

0
1
0

Upvotes: 0

Views: 129

Answers (4)

Amadan
Amadan

Reputation: 198388

perl -pe 's/^(\d+)/sprintf("%03b",$1)/e' inputfile.txt

s///e will execute the replacement as Perl code and replace the match with the result, leaving the rest unchanged.

perl -pe 's/^(\d).*/$1/' inputfile.txt

for the first character, but there are easier non-regex ways:

cut -c1 inputfile.txt

Upvotes: 2

velz
velz

Reputation: 29

you can split to get the first column and use sprintf to convert decimal  to binary number

use lexical filehandle so that u can avoid closing the filehandle. 

select is used to write the content to a new file.

#!/usr/bin/perl
use strict;
use warnings;

open my $fh, '<',"num.txt" || die "$!";
open my $wh , '>',"op.txt" || die "$!";
select ($wh);
while (my $line = <$fh>)
{
   chomp($line);
   my @aRR = split (/\s/,$line);
   my $bin = sprintf("%03b",$aRR[0]);
   print $bin," ",$aRR[1]," ", $aRR[2],"\n";
}

Upvotes: 0

Matt Jacob
Matt Jacob

Reputation: 6553

Use -a (autosplit mode) to split on whitespace, but only modify the first column with your conversion and print the other columns unchanged:

$ perl -wane '$F[0] = sprintf("%03b", $F[0]); print "@F\n";' input.txt

Output:

011 4 5
110 7 2
001 2 3

Upvotes: 1

russdot
russdot

Reputation: 685

You can use regex anchors to achieve what you want. A regular expression like ^\d would match a single digit at the beginning of a line.

If you need to support multi-digit numbers (like 15 or 123, for example) you can add a repetition operator: ^\d+ will match any multi-digit number at the beginning of a line.

Upvotes: -1

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