Beefy Boxes and Bandwidth Generously Provided by pair Networks
go ahead... be a heretic
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Actually it's not too difficult to fix your problem, and I can point out the issue along the way.

First, you should understand that in your first example, the loop is iterating over the actual scalar variables, $name, $nerd, $noodle, $froodle. And $item is aliasing (or "is a") those scalars. When you change $item, via the substitution, you change value of the variable that it represents; being $name, $nerd, $noodle, and $froodle, depending on the iteration of the loop.

In your second example, you are assigning the values contained in the scalar variables $name, $nerd, $noodle, and $froodle, to an array named @look_for. But what that means is that @look_for just contains a list of values, not a list of scalar variables.

So in your second example, when you iterate over each element contained in @look_for, $item becomes an alias for $look_for[0], in the first iteration, $look_for[1] in the second iteration, etc. And as you recall, those elements contain the values that were passed to them by $name, $nerd, etc. The distinction is that at this point, $name, $nerd, and so on, are no longer associated, in any way, with @look_for.

The result is that as you change $item in the second example, you're changing the value of elements of @look_for, not the value of the variables $name, and so on.

If you intend to use the second example, you need to give @look_for references to the scalar variables $name, $nerd, $noodle, and $froodle, instead of just the values. That way, each element of @look_for refers to the original scalar variables. Then, inside the loop, you must dereference $item to change the value of the scalar variable referenced by the array element $item aliases. Here is a working example:

my @look_for = ( \$name, \$nerd, \$noodle, \$froodle ); foreach my $item ( @look_for ) { $$item =~ s/$i_seek/ /g; }

Now you'll find that you're modifying the value of the original scalar variables pointed to (in C-speak) or referred to (in Perl-speak) by the elements in @look_for. Just remember to always dereference the elements in @look_for when you mean to modify the values of the variables they point to.

I hope this is helpful. I recommend reading the perldoc on references, and on lists of lists, as both will aid you in understanding how this works.

Dave "If I had my life to do over again, I'd be a plumber." -- Albert Einstein


In reply to Re: array confusion by davido
in thread array confusion by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others exploiting the Monastery: (2)
As of 2022-01-29 08:00 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    In 2022, my preferred method to securely store passwords is:












    Results (74 votes). Check out past polls.

    Notices?