Normal people count from 1. Computer Scientist count from 0. Perl developers count from -1?
WTF?
oz@server ~ $ test.pl test num of args 0 oz@server ~ $ test.pl test test num of args 1 0 test 1 test oz@server ~ $ test.pl num of args -1 No arguments! oz@server ~ $My Code, just in case I am totally wrong about this here, :
$ cat test.pl
#!/usr/local/bin/perl -w
print "num of args $#ARGV \n";
if ( $#ARGV > 0 ){
for ( my $i = 0 ; $i <= $#ARGV ; ++$i ) {
print "$i\n";
print "$ARGV[$i]\n";
}
}
if ( @ARGV > 0 )
{
print "Number of arguments: " . scalar @ARGV . "\n";
}
else
{
print "No arguments!\n";
}
4 comments:
$#ARGV is not the number of args. It's the last index of array @ARGV. I agree that the $# thing is weird, but you hardly ever need to use it.
scalar @ARGV is indeed the number of args.
You also hardly ever have to use the C-style "for( initialization; condition; increment)" loop. It's nicer to do:
my $idx = 0;
foreach my $arg (@ARGV) {
print $idx++ . ": $arg\n";
}
Read these pages some time:
* http://perldoc.perl.org/perlsyn.html
* http://perldoc.perl.org/perldata.html
Thanks Amir, I know it's a silly rant :-)
But it's already weired for a lot of people to start counting from Zero (Fortran and Matlab start from 1). Now, I need to get used to counting from -1.
Well no, counting from 0 is a common standard to which Perl adheres. It doesn't count from -1.
my @array = (0, 1, 2, 3);
print scalar @array; # 4
print $#array; # 3
print $array[0]; # 0
Now get this:
print $array[-1]; # 3
print $array[-2]; # 2
BTW, if you use at least Perl 5.10, put
use 5.010;
in the beginning, and use "say" instead of "print".
Hi Amir,
Is there is significant difference between print and say ?
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