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.
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 $. variable too, which is the line number of the last line read from the last filehandle you read from. It, too, is in perlvar. And the program uses a nice, fair algorithm
for choosing a random line.
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omni posted this at 07:15 — 19th October 2000.
They have: 32 posts
Joined: Oct 2000
I think he ment to say local($_), 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
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japhy posted this at 11:49 — 19th October 2000.
They have: 161 posts
Joined: Dec 1999
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.
Orpheus posted this at 20:46 — 19th October 2000.
They have: 568 posts
Joined: Nov 1999
Nope, I mean $\ not $_
japhy posted this at 21:25 — 19th October 2000.
They have: 161 posts
Joined: Dec 1999
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 posted this at 05:08 — 21st October 2000.
They have: 568 posts
Joined: Nov 1999
We all make typos when we're out of coffee.
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