push @a;
[download]

push @a, $_;
[download]

Well, yes, actually I did. I thought that

push @a;

was equivalent to

push @a, $_;

in the same manner that

print;

is equivalent to

print $_;

Maybe I need to brush up on when $_ has to be used and when i can be omitted.

Is there a good ref material or camel chapter on this?

Ed

perldoc -f push doesn't say anything about defaulting to $_. Also, looking up push in the Camel doesn't show the $_ box like it does for print (which is, conveniently, on the facing page in my Camel 3rd ed.)

But I'm not criticizing, I might have made the same assumptions.

This is how I try to remember this.  push takes a list as argument and hence  $_ cannot be taken as a default argument for this.

Update But then as Smylers pointed out  print also takes a list of arguments but still takes $_ as default argument when there is none. puzzling ??

-T

use perl; use strict;

But, having said that, I have tried my code as you suggest and still get no results.

cat file | perl -e "while (<>) { push @a, $_; } print join(',',@a);"
[download]

Ed

Try switching the double quotes for single quotes, and the single quotes for double quotes.

Here is yet another way to do it:

perl -le 'print join ",",map{chomp;$_}<>' file
[download]

-enlil

Is there a reason that $_ shouldn't be a default argument for push? That is, would it be a Bad Idea for future versions?

Also, do you find that the • in your titles renders a bullet? It doesn't for me, though it does produce a bullet when used in the body. Why do you do it?

BTW, That's a useless use of cat.

Update: Here's an alternative to avoid reading the whole file into memory:

perl -e '{ $_=<>; chomp; print; last if eof(); print ","; redo }; prin
+t $/'
[download]

-sauoq
"My two cents aren't worth a dime.";

perl -e "chomp(@F=<>); print join',',@F" file
[download]

perl -pe "tr/\n/,/" file
[download]

perl -l0054pe '' file
[download]

perl -pe "eof or tr/\n/,/" file
[download]

    perl -lpe '$\=(eof)?$/:","' file
[download]

Update: or this

    perl -l54pe '$\=$/if+eof'   file
[download]

--
John.

You've still got me by one character... perl -0pe 'y/\n/,/;s/,$/\n/'

Update: But, wait!

perl -0pe 's/\n(?!$)/,/g'
[download]

:-)

-sauoq
"My two cents aren't worth a dime.";

This was a gimme from my earlier post. It's also fairly readable. Compared to yours, the expression is 1 char shorter, and there's one fewer command-line option.

perl -pe  'eof||y/\n/,/'
[download]

So it's golf, is it? :-)

perl -lpe '$\=!eof&&","'
[download]

Update: Uh, hmm, just realized that doesn't quite do the same thing (gets rid of the trailing newline). Bah, details.

-- Mike

--
XML::Simpler does not require XML::Parser or a SAX parser. It does require File::Slurp.
-- grantm, perldoc XML::Simpler

Update: Added -0777 and split /\n/ per sauoq's comment

He doesn't want output like:

foo
,bar
,baz
[download]

That -l doesn't chomp unless it is used with -n or -p. I made the same mistake and quickly corrected it.

-sauoq
"My two cents aren't worth a dime.";