perl - Backslash before a subroutine call -

as understanding difference between [] , \ in references,i used both on subroutine former fine when tried later thought should give error below program in perl

#!/usr/bin/perl use strict; use warnings; use data::dumper;  @b; $i ( 0 .. 10 ) {     $b[$i] = \somefunc($i);  } print dumper( \@b );  sub somefunc {     $n = shift;     ( @a, $k );     $j ( 11 .. 13 ) {         $k = $n * $j;         push( @a, $k );     }     print "a: @a \n";     return @a; } 

gives output :

a: 0 0 0  a: 11 12 13  a: 22 24 26  a: 33 36 39  a: 44 48 52  a: 55 60 65  a: 66 72 78  a: 77 84 91  a: 88 96 104  a: 99 108 117  a: 110 120 130  $var1 = [       \0,       \13,       \26,       \39,       \52,       \65,       \78,       \91,       \104,       \117,       \130     ]; 

i unable understand output.need explanation.

what happening here is:

you returning array somefunc.

but assigning scalar. effectively doing therefore, putting last value in array, scalar value.

my $value =  ( 110, 120, 130 ); print $value; 

when - $value set last value in array. what's happening in code. see example perldata:

list values denoted separating individual values commas (and enclosing list in parentheses precedence requires it): (list)

in context not requiring list value, value of appears list literal value of final element, c comma operator. example,

@foo = ('cc', '-e', $bar);

assigns entire list value array @foo, but

foo = ('cc', '-e', $bar);

assigns value of variable $bar scalar variable $foo. note value of actual array in scalar context length of array; following assigns value 3 $foo:

@foo = ('cc', '-e', $bar); $foo = @foo; # $foo gets 3

it's latter case that's gotcha, because it's list in scalar context.

and in example - backslash prefix denotes 'reference to' - largely meaningless because it's reference number.

but scalar, might more meaningful:

my $newvalue = "fish";  $value =  ( 110, 120, 130, \$newvalue ); print dumper $value;  $newvalue = 'barg';  print dumper $value; 

gives:

$var1 = \'fish'; $var1 = \'barg'; 

that's why you're getting results. prefix slash indicates you're getting reference result, not reference sub. reference 130 isn't meaningful.

normally, when doing assignment above - you'd warning useless use of constant (110) in void context doesn't apply when you've got subroutine return.

if wanted insert sub reference, you'd need add &, if want insert returned array reference - either need to:

$b[$i] = [somefunc($i)] 

or:

return \@a;