Default value of $#ArrayName when there is no element (Perl) -


the code below display number of arguments entered in command line.

#!/usr/bin/perl –w $myvar = $#argv + 1; print "hi " , $argv[0] , "\n"; print "you have $myvar arguments\n";

from perlintro, $#argv special variable tells index of last element of array.

if case, when don't enter value in command line, how $myvar value end 0 ?

is because when there no element in array, index of "no element" -1 ? -1 + 1 = 0.

$#argv means "the index of last element of argv" - not array perlintro sentence seems imply.

for array, if it's empty, $#array -1 , scalar @array 0.

caveat: if has modified $[ ("index of first element"), that'll change $# well. should probably use scalar @array if you're after length, , $array[-1] last element.

> cat demo.pl @array = (); print "size=", scalar @array, " items, last=", $#array, "\n"; $[ = 2; print "size=", scalar @array, " items, last=", $#array, "\n"; > perl demo.pl size=0 items, last=-1 size=0 items, last=1

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