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Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question: (input and output)

I found it is possible to use print function in the following way:
$a=4; $b=5; print " Something = $a Something else = $b ";
It makes newlines itself! I didn't find anything like this in documentation and FAQs. stasoft@yahoo.com

Originally posted as a Categorized Question.

Replies are listed 'Best First'.
Re: Funny usage of print function
by davido (Cardinal) on Sep 13, 2003 at 21:44 UTC
    If you want to embed newlines in your output (or any string) you shouldn't be doing it like this,

    my $a; $a = " Some stuff here Some more stuff on the next line ";

    Although this works in some cases, you could concievably run into trouble when you take a script with such embedded newlines from a *nix type OS to a M$ operating system.

    The other problem with embedding invisible newlines in quoted strings is that it is difficult to tell the difference between wrapped text and text with newlines. And it is difficult to find the end of the string. People just don't expect " quoted " text to span multiple lines. At very least, use the visible version of newline, "\n".

    A more efficient and foolproof way of doing it if you have multiple lines of literal text is to use here documents. Here documents can be used directly within a print statement, or in an assignment statement, or anywhere else that a string is expected. Here's an example:

    my $string = <<END_HERE; Here is some text. Newlines, though invisible, are implicitly understood, and in fact, are expected. A here document won't confuse people. END_HERE

    As I mentioned before, here documents can also be used directly within a print statement:

    print << END_HERE; Here is multi-line text created with a here document. END_HERE

    An interesting thing about here documents is that the text is assumed to be "double quoted" unless you wrap the leading marker in some other type of quotes. And as we all know, double-quoted text is subject to variable interpolation as well as "\n" conversion. So each of the following examples use a different sort of quoting:

    my $string; $string = <<END_HERE; # Seen as double quotes. text END_HERE $string = <<"END_HERE"; # Same thing. $string = <<'END_HERE'; # Interpolated as 'single quotes'. $string = <<`END_HERE`; # Interpolated as `backtick` quoted text. or even..... ( $string <<END_HERE ) =~ s/^\s+//gm; indented text becomes unindented because the substitution regexp removes preceding whitespace. END_HERE ...and so on.

    I dove into this response because I was concerned when I saw in the Q&A section the promotion of using multiline "quoted" text with embedded invisible newlines. Yes, it can work. Yes, it can be quite confusing. Yes, that's what here-docs are for.

Re: Funny usage of print function
by chromatic (Archbishop) on Mar 20, 2000 at 23:29 UTC
    If you have a newline embedded in a quoted string (single or double both work for me), Perl will include it when printing:
    print "a b c d";
    prints
    a b c d
    while print "a b c d"; prints a b c d Check for line breaks in your code.
Re: Funny usage of print function
by comatose (Monk) on May 12, 2000 at 08:24 UTC

    You should also be aware that most likely, it will work unexpectedly on different operating systems. If you have a Unix formatted script and try to run it on Win32, you'll get the same results as if you just used \n.

Re: Funny usage of print function
by Anonymous Monk on Apr 19, 2001 at 08:25 UTC
    Yeah, that works in C too... and probably in many other languages too...here is an example of this in C....It's very useful...especially if you don't want to type printf...or in PERL, print, 15 billion times :D...This message is almost pointless, besides that I wanted to show it works in C too :D...... /* Code Showing how to print multiple lines without the \n being passed in C Author: Obfuscated C */ #include <stdio.h> main() { printf (" Hey this is the how to have multiple lines printed the BETTER way!! "); return 0; }

    Originally posted as a Categorized Answer.

Re: Funny usage of print function
by Anonymous Monk on Apr 19, 2001 at 08:28 UTC
    Darn, that was a horrible post :D.........ummm.. it should have been #include <stdio.h>....next time, i'll learn how to format the text here better sorry if you couldn't translate the C code.... :) Heck, I didn't realize it would turn out that way!!

    Originally posted as a Categorized Answer.