Find and Replace in Textfile

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Recently, I was asked to find the first occurrence of a word in a text file=
and replace it with an alternate word.=A0 This was my solution.=A0 As a ne=
w Perl programmer, I feel like this solution was too C like and not enough =
Perl like.=A0 So, my question is what would have been the Perl like solutio=
n to this problem?=A0 =0AIn this example there is little risk of runn=
ing out of memory reading the file.=A0 But had this been a production envir=
onment or an unknown file size, I would have had to consider that.   =
=0A#!/usr/bin/perl=0Ause strict;=0Ause warnings; #program finds =
the first occurrence of the word Dood and =0A#replaces it with the word Dud=
e in the file data.txt. open FP, "+<", "data.txt" || die "Cant open da=
ta.txt " . $!; my @buffer =3D ;=0Aseek FP,0,0;=0Amy $do_replace =
=3D 1; #used to control replacing in multiline files.=0Amy $line;=0Amy $dat=
a;=0Aforeach $data (@buffer)=0A{     if ($do_replace == 1)=0A=
  =A0 {  =A0       =A0 $line =3D $data;     =
  =A0 $data =3D~ s/Dood/Dude/;       =A0 if ($line ne $data=
)       =A0 {       =A0   =A0 $do_replace =3D 0=
; #we did a substitution so do no more.       =A0 }    =
}     print FP $data;=0A}=0Aclose FP; #Test data=0A#Dude! Whe=
re's my car?=0A#Dood! Where's my car?=0A#Dood! Where's my car?   =
=0A--=0ARonald Weidner
--0-1251182583-1313926412=:76716--

Re: Find and Replace in Textfile

On 11-08-21 07:33 AM, Ron Weidner wrote:
> Recently, I was asked to find the first occurrence of a word in a text file and replace it with an alternate word. This was my solution. As a new Perl programmer, I feel like this solution was too C like and not enough Perl like. So, my question is what would have been the Perl like solution to this problem?
>

IO::Insitu http://search.cpan.org/~dconway/IO-InSitu-0.0.2/lib/IO/InSit u.pm


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Re: Find and Replace in Textfile

On 21/08/2011 12:33, Ron Weidner wrote:
>
> Recently, I was asked to find the first occurrence of a word in a
> text file and replace it with an alternate word. This was my
> solution. As a new Perl programmer, I feel like this solution was too
> C like and not enough Perl like. So, my question is what would have
> been the Perl like solution to this problem?
>
> In this example there is little risk of running out of memory
> reading the file. But had this been a production environment or an
> unknown file size, I would have had to consider that.
>
>
> #!/usr/bin/perl
> use strict;
> use warnings;
>
> #program finds the first occurrence of the word Dood and
> #replaces it with the word Dude in the file data.txt.
>
> open FP, "+<", "data.txt" || die "Cant open data.txt " . $!;
>
> my @buffer =;
> seek FP,0,0;
> my $do_replace = 1; #used to control replacing in multiline files.
> my $line;
> my $data;
> foreach $data (@buffer)
> {
> if ($do_replace == 1)
> {
> $line = $data;
> $data =~ s/Dood/Dude/;
> if ($line ne $data)
> {
> $do_replace = 0; #we did a substitution so do no more.
> }
> }
> print FP $data;
> }
> close FP;
>
> #Test data
> #Dude! Where's my car?
> #Dood! Where's my car?
> #Dood! Where's my car?

Hey Ronald

Here is a program like yours, that reads the entire file into memory and
then outputs the altered version.

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

#program finds the first occurrence of the word Dood and
#replaces it with the word Dude in the file data.txt.

open my $fp, "<", "data.txt" or die "Cant open data.txt for input: $!";
my @buffer = <$fp>;

open my $fp, ">", "data.txt" or die "Cant open data.txt for output: $!";
my $replaced;

foreach my $line (@buffer) {
unless ($replaced) {
$replaced++ if $line =~ s/Dood/Dude/;
}
}
__END__

But if you may be working with large files and have to be careful with
memory, it is best to process the input file one line at a time. There
are special built-in ways of doing this sort of thing, but it is best
for now to write something that is clear and straightforward. Something
like this perhaps.

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

#program finds the first occurrence of the word Dood and
#replaces it with the word Dude in the file data.txt.

rename 'data.txt', 'data.old' or die "Rename of input file failed: $!";
open my $in, '<', 'data.old' or die "Failed to open input file: $!";
open my $out, '>', 'data.txt' or die "Failed to open output file: $!";

my $replaced;
while (my $line = <$in>) {
unless ($replaced) {
$replaced++ if $line =~ s/Dood/Dude/;
}
print $out $line;
}
__END__


I hope this helps,

Rob

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Re: Find and Replace in Textfile

On 21/08/2011 13:21, Rob Dixon wrote:
>
> Hey Ronald
>
> Here is a program like yours, that reads the entire file into memory and
> then outputs the altered version.
>
> #!/usr/bin/perl
> use strict;
> use warnings;
>
> #program finds the first occurrence of the word Dood and
> #replaces it with the word Dude in the file data.txt.
>
> open my $fp, "<", "data.txt" or die "Cant open data.txt for input: $!";
> my @buffer =<$fp>;
>
> open my $fp, ">", "data.txt" or die "Cant open data.txt for output: $!";
> my $replaced;
>
> foreach my $line (@buffer) {
> unless ($replaced) {
> $replaced++ if $line =~ s/Dood/Dude/;
> }
> }
> __END__

I'm sorry - that wasn't the version I tested! Here is the correct
working program. The second program I posted works fine.

Rob

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

#program finds the first occurrence of the word Dood and
#replaces it with the word Dude in the file data.txt.

my $fp;
open $fp, "<", "data.txt" or die "Cant open data.txt for input: $!";
my @buffer = <$fp>;

open $fp, ">", "data.txt" or die "Cant open data.txt for output: $!";
my $replaced;

foreach my $line (@buffer) {
if (not $replaced) {
$replaced++ if $line =~ s/Dood/Dude/;
}
print $fp $line;
}
__END__

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Re: Find and Replace in Textfile

>>>>> "SHC" == Shawn H Corey writes:

SHC> On 11-08-21 07:33 AM, Ron Weidner wrote:
>> Recently, I was asked to find the first occurrence of a word in a text file and replace it with an alternate word. This was my solution. As a new Perl programmer, I feel like this solution was too C like and not enough Perl like. So, my question is what would have been the Perl like solution to this problem?
>>

SHC> IO::Insitu http://search.cpan.org/~dconway/IO-InSitu-0.0.2/lib/IO/InSit u.pm

even simpler is File::Slurp::edit_file

uri

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Re: Find and Replace in Textfile

Ron Weidner wrote:
> Recently, I was asked to find the first occurrence of a word in a text
> file and replace it with an alternate word. This was my solution. As
> a new Perl programmer, I feel like this solution was too C like and
> not enough Perl like. So, my question is what would have been the
> Perl like solution to this problem?
>
>
> In this example there is little risk of running out of memory reading
> the file. But had this been a production environment or an unknown
> file size, I would have had to consider that.
>
>
> #!/usr/bin/perl
> use strict;
> use warnings;
>
> #program finds the first occurrence of the word Dood and
> #replaces it with the word Dude in the file data.txt.
>
> open FP, "+<", "data.txt" || die "Cant open data.txt " . $!;
>
> my @buffer =;
> seek FP,0,0;
> my $do_replace = 1; #used to control replacing in multiline files.
> my $line;
> my $data;
> foreach $data (@buffer)
> {
> if ($do_replace == 1)
> {
> $line = $data;
> $data =~ s/Dood/Dude/;
> if ($line ne $data)
> {
> $do_replace = 0; #we did a substitution so do no more.
> }
> }
> print FP $data;
> }
> close FP;
>
> #Test data
> #Dude! Where's my car?
> #Dood! Where's my car?
> #Dood! Where's my car?

There are a few ways to do what you require:

#!/usr/bin/perl
use strict;
use warnings;
use Tie::File

tie my @buffer, 'Tie::File', 'data.txt' or die "Cant open data.txt $!";

for ( @buffer ) {
s/Dood/Dude/ and last;
}

__END__


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

local ( $^I, @ARGV ) = ( '', 'data.txt' );

while ( <> ) {
?Dood? && s/Dood/Dude/;
print;
}

__END__


#!/usr/bin/perl
use strict;
use warnings;
use Fcntl ':seek';

open my $FP, '+<', 'data.txt' or die "Cant open data.txt $!";
read $FP, my $buffer, -s $FP or die "Cant read from data.txt $!";
seek $FP, 0, SEEK_SET or die "Cant seek on data.txt $!";
$buffer =~ s/Dood/Dude/;
print $FP $buffer;

__END__



John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein

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Re: Find and Replace in Textfile

>>>>> "JWK" == John W Krahn writes:

JWK> There are a few ways to do what you require:

and you missed the simplest one so far (i did mention edit_file):

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

use File::Slurp qw( edit_file ) ;

edit_file { s/Dood/Dude/g } $file ;

and if you need a counter:

my $change_cnt ;

edit_file { $change_cnt = s/Dood/Dude/g } $file ;

$change_cnt ||= 0 ;

print "made my $change_cnt ;


JWK> tie my @buffer, 'Tie::File', 'data.txt' or die "Cant open data.txt $!";

JWK> for ( @buffer ) {
JWK> s/Dood/Dude/ and last;
JWK> }

JWK> __END__


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

JWK> local ( $^I, @ARGV ) = ( '', 'data.txt' );

JWK> while ( <> ) {
JWK> ?Dood? && s/Dood/Dude/;
JWK> print;
JWK> }

JWK> __END__


JWK> #!/usr/bin/perl
JWK> use strict;
JWK> use warnings;
JWK> use Fcntl ':seek';

JWK> open my $FP, '+<', 'data.txt' or die "Cant open data.txt $!";
JWK> read $FP, my $buffer, -s $FP or die "Cant read from data.txt $!";
JWK> seek $FP, 0, SEEK_SET or die "Cant seek on data.txt $!";
JWK> $buffer =~ s/Dood/Dude/;
JWK> print $FP $buffer;

JWK> __END__



JWK> John
JWK> --
JWK> Any intelligent fool can make things bigger and
JWK> more complex... It takes a touch of genius -
JWK> and a lot of courage to move in the opposite
JWK> direction. -- Albert Einstein

JWK> --
JWK> To unsubscribe, e-mail: beginners-unsubscribe@perl.org
JWK> For additional commands, e-mail: beginners-help@perl.org
JWK> http://learn.perl.org/





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Re: Find and Replace in Textfile

>>>>> "JWK" == John W Krahn writes:

JWK> There are a few ways to do what you require:

and you missed the simplest one so far (i did mention edit_file):

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

use File::Slurp qw( edit_file ) ;

my $file = 'data.txt' ;

edit_file { s/Dood/Dude/g } $file ;

and if you need a counter:

my $change_cnt ;

edit_file { $change_cnt = s/Dood/Dude/g || 0 } $file ;

print "made $change_cnt changes to $file\n" ;

uri

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Re: Find and Replace in Textfile

>>>>> "John" == "John W Krahn" writes:

John> ?Dood? && s/Dood/Dude/;

Deprecated in 5.14. Replace with m?Dood? and you're good though.

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Re: Find and Replace in Textfile

On Aug 21, 4:33=A0am, xecro...@yahoo.com (Ron Weidner) wrote:
> Recently, I was asked to find the first occurrence of a word in a text fi=
le and replace it with an alternate word.=A0 This was my solution.=A0 As a =
new Perl programmer, I feel like this solution was too C like and not enoug=
h Perl like.=A0 So, my question is what would have been the Perl like solut=
ion to this problem?=A0
>
> In this example there is little risk of running out of memory reading the=
file.=A0 But had this been a production environment or an unknown file siz=
e, I would have had to consider that.  
>
> #!/usr/bin/perl
> use strict;
> use warnings;
>
> #program finds the first occurrence of the word Dood and
> #replaces it with the word Dude in the file data.txt.
>
> open FP, "+<", "data.txt" || die "Cant open data.txt " . $!;
>
> my @buffer =3D ;
> seek FP,0,0;
> my $do_replace =3D 1; #used to control replacing in multiline files.
> my $line;
> my $data;
> foreach $data (@buffer)
> {
>   =A0 if ($do_replace == 1)
>   =A0 {  =A0
>   =A0   =A0 $line =3D $data;
>   =A0   =A0 $data =3D~ s/Dood/Dude/;
>   =A0   =A0 if ($line ne $data)
>   =A0   =A0 {
>   =A0   =A0   =A0 $do_replace =3D 0; #we did a substitution s=
o do no more.
>   =A0   =A0 }
>   =A0 }
>   =A0 print FP $data;}
>
> close FP;
>
> #Test data
> #Dude! Where's my car?
> #Dood! Where's my car?
> #Dood! Where's my car?
>
> =A0

If you're permitted a one-liner:

perl -pi.bak -e '$c=3Ds/Dood\/Dude/ if !$c++' file

--
Charles DeRykus


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Re: Find and Replace in Textfile

C.DeRykus wrote:
>
> If you're permitted a one-liner:
>
> perl -pi.bak -e '$c=s/Dood\/Dude/ if !$c++' file

$ perl -c -pi.bak -e '$c=s/Dood\/Dude/ if !$c++'
Substitution replacement not terminated at -e line 1.



John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein

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