How to eval an array element in regex's substitution

[pysome]

How to eval an array element in regex's substitution ?
Dear All,
I wanna get "Hello zy" in following code. I try to add /e and /ee, all they can't work.

my $s       = 'Hello [2][1]';
my @a       =('x','y','z');
my $replace ='$a';
$s          =~ s/(\[\d{1,2}\])/$replace\1/g;  ## only output : Hello $
+a[2]$a[1]
print $s;

Pls give me a hand. THX.

Regards

-Pysome

[ikegami]

First, \1, etc are regex patterns. You want $1, etc.

Secondly, you have some serious misconception about the replacement expression.
Without /e, it's a double-quoted string literal that evaluates to the replacement.
With /e, it's a Perl expression which evaluates to the replacement.

my $s = 'Hello [2][1]';
my @a = ('x','y','z');
$s =~ s/\[(\d{1,2})\]/$a[$1]/g;
print $s;

[pysome]

Thank your very much.
Another question, maybe i refer to capture the square brackets ,
and then "eval" the array element. Such as:


$s =~ s/(\[\d{1,2}\])/$a$1/g; #output Hello $a[2]$a[1]

# eval '$s="$s";'; ## Here ?

How to eval the $s's value？

[ikegami]

my $s = 'Hello [2][1]';
my @a = ('x','y','z');
my $array_name = 'a';
{
   no strict 'refs';
   $s =~ s/\[(\d{1,2})\]/$array_name->[$1]/g;
}
print $s;

Better:

my $s = 'Hello [2][1]';
my @a = ('x','y','z');
my $array_name = 'a';
my $array_ref = do { no strict 'refs'; \@$array_name };
$s =~ s/\[(\d{1,2})\]/$array_ref->[$1]/g;
print $s;

But why do you want to use variable variable names?

Good:

my $s = 'Hello [2][1]';
my @a = ('x','y','z');
my $array_ref = \@a;
$s =~ s/\[(\d{1,2})\]/$array_ref->[$1]/g;
print $s;

Simplified:

my $s = 'Hello [2][1]';
my @a = ('x','y','z');
$s =~ s/\[(\d{1,2})\]/$a[$1]/g;
print $s;

[aquarium]

In the scope/context provided, it doesn't make sense to use regex to achieve "Hello zy". If it's always going to be "Hello " followed by index 2 and index 1 of @a array, then just make it: my $s = 'Hello ' . $a[2] . $a[1]; which can be easily parametarised in that format. Or even use splice. why the regex?

[aquarium]

oh i get it, i think...this is the continuing saga of a mail merge. in my own opinion, you need to learn a bit more about *nix utilities, networking protocols (smtp for a start), and programming (the design aspect). otherwise you'll end up throwing together "solutions" that hang by a thread. it's not a criticism of you or your knowledge, but you seem to have currently a level of knowledge where you could make something nice or a mess. you need (i think) a more rigorous structure/modularity in your code and overall approach. which means more thinking and less coding. like everything else here this is just an opinion and you can just ignore it.

[Anonymous Monk]

Maybe you think it simply.
The $s is dynamic.It is maybe  "[2][1]" or maybe "[9]  [8] [3]",
. I only wanna to replace the  [xx]with a fix array's element.
But the rule is , the  [xx] is index of the array!