Read lines from a textfile 2

[Virrum]

Hi,
I've never looked at a perl script before, but I'd like to modify a fragment of a bigger program. So I'd like to ask you this:

sub RewriteFile {
my ($file, $tmpfile) = @_;
my $i;
my $temporary;
if (!open (IN, "$file")) {
print "Couldn't open input file $file\n";
return 0;
}
if (!open (TEMP, ">$tmpfile")) {
print("Couldn't open temporary file $tmpfile\n");
return 0;
}
binmode TEMP;
binmode IN;
while (<IN>) {
s/\r?\n$/\n/;
s/\r/\n/g;
$_ = &TabConversion($_);
# Walk through the line and see if it longer than MaxChars.
if (length($_) >= $MaxChars) {
print TEMP substr($_, 0, $MaxChars);
print TEMP "\n";
print TEMP substr($_, $MaxChars);
}
else {
print TEMP "$_";
}
}
print TEMP "\n";
close(IN);
close(TEMP);
return 1;
}

sub TabConversion {
my $line=shift(@_);
while($line=~/([^\t]*)\t/) {
my $spaces="";
my $spaceNO=$SpacesPerTab-(length $1)%$SpacesPerTab;
for (1..$spaceNO) {$spaces.=" ";}
$line =~ s/([^\t]*)\t/$1$spaces/;
}
return $line;
}


This script reads a text file, and writes a tmp file.

I'd like to just write line number 10 of that file. Can anybody help me with that?

thanks a lot in advance.

 

[1DMF]

put a counter in and when = 10 print line!

 binmode TEMP;
    binmode IN;
   [b] my $counter=0;[/b]
    while (<IN>) {
        [b]$counter++;[/b]
        s/\r?\n$/\n/;
        s/\r/\n/g;
        $_ = &TabConversion($_);
        # Walk through the line and see if it longer than MaxChars.
      [b]if($counter == 10){[/b]
        if (length($_) >= $MaxChars ) {
            print TEMP substr($_, 0, $MaxChars);
            print TEMP "\n";
            print TEMP substr($_, $MaxChars);
        }
        else {
            print TEMP "$_";
        }
      [b]}[/b]
    }
    print TEMP "\n";
    close(IN);
    close(TEMP);
    return 1;
}

"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you."

"If a shortcut was meant to be easy, it wouldn't be a shortcut, it would be the way!

 

[brigmar]

Inside your while() loop, just tell it to only process the 10th line.
while(<IN>) {
if($. == 10) {
...
...
...
}
}

 

[1DMF]

whats $. as a var?

I know @_ , $_ but not $.

"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you."

"If a shortcut was meant to be easy, it wouldn't be a shortcut, it would be the way!

 

[Virrum]

Hi,
Thanks a lot! While you're in that theme, what is $_ and @_?

 

[brigmar]

$. is the record counter of the last file you just read from.

print "$. = $_" while (<DATA>);

__DATA__
First Line
Second Line
Third Line
Fourth Line

 

[brigmar]

$_ and @_ :

http://www.wellho.net/mouth/969_Perl-and-.html

 

[1DMF]

cool as nice one Brigmar,

if you are doing a loop for example

for(@myarray){

print $_;

}

would $. equal anything in that senario?

"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you."

"If a shortcut was meant to be easy, it wouldn't be a shortcut, it would be the way!

 

[brigmar]

No; You're looping through an array, not a file there.

 

[KevinADC]

Here is a list of all of perls predefined variables:

http://perldoc.perl.org/perlvar.html

all perl coders should try an be familiar with them.

------------------------------------------
- Kevin, perl coder unexceptional!

 

[1DMF]

IC Brigmar, I was just applying the logic of the $ var to the loop, but alas, it doesn't work that way, would be cool if it did

thanks Kevin appreciated.

"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you."

"If a shortcut was meant to be easy, it wouldn't be a shortcut, it would be the way!