backwards ;)

japhy — Thu, 19 Oct 2000 21:25:11 +0000

You have it a bit backwards, then, Orpheus... $\ is
the output record separator. That is:

print 1; print 2; print 3; # prints "123"
$\ = "#";
print 1; print 2; print 3; # prints "1#2#3#"
$\ = " ";
print 1; print 2; print 3; # prints "1 2 3 "
$\ = ",";
print 1; print 2; print 3; # prints "1,2,3,"

I think you meant the $/ variable...

Orpheus — Thu, 19 Oct 2000 20:46:33 +0000

Nope, I mean $\ not $_

perldoc perlvar

japhy — Thu, 19 Oct 2000 11:49:42 +0000

There are more punctuation variables than just $_, you know. The $/ variable is the input record separator. It defaults to a newline "\n", but if you change it, you can change the meaning of a "line".

For example, if you want to read the sections of a fortune file, they're formatted like this:

Funny quote here...
%%
Here's another quote that spans more than two
Lines, so it'd be annoying to use \n as
the record separator, no?
%%
Etc.

So that's where $/ becomes handy. Even better, when you chomp(), you're not just removing an ending newline from a string, you're removing an ending $/ from the string. And the variable has two special values, the empty string "", and undef. Check perlvar for more info.

randfortune

#!/usr/bin/perl
 
$/ = "%%\n";
open FORTUNE, shift or die "usage: randfortune FILE\n";
while (<FORTUNE>) {
  if (rand($.) < 1) { $line = $_ }
}
close FORTUNE;
chomp $line;
print $line;

That nifty little program reads a fortune-style file and gives you a random entry. It uses the $. variable too, which is the line number of the last line read from the last filehandle you read from. It, too, is in perlvar. And the program uses a nice, fair algorithm
for choosing a random line.

omni — Thu, 19 Oct 2000 07:15:54 +0000

I think he ment to say local($_), the local() means to keep whatever variables in the brackets local to the function in perl. The $_ variable is a special variable that will give you the last result of a function or calling function.

Greg