in reply to Problem with parameters in subroutines

Others have already answered your more immediate question, but from the way you asked, it looks like you may have a misconception about how subroutine parameters work in the first place.

All that passing parameters to a subroutine call does, is to make those values available to the subroutine in the special @_ array.
It does not automatically make each parameter a variable inside the subroutine, and in fact it won't have any effect at all if the subroutine does not choose to look at the contents of @_.

Often, "looking at the contents of @_" is done implicitly using calls to shift, hence the  my $candidate = shift; in the above answer.

If you need more explanation, please read perlintro#Writing-subroutines.

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Re^2: Problem with parameters in subroutines
by aatrox (Initiate) on Jun 02, 2014 at 14:05 UTC
    Ok thanks for explanation. Im already learning perl from yesterday and sometimes it looks strange for me :) I have got next question with loops: If i have got loop: 
     foreach $guest(@people)
        {
            if($guest->{'ident'} =~ /^1[014689]*7[014689]*5[014689]*3[
+014689]*2[014689]*$/)
            {
                 mywrite($guest);  #my print function
                  
            }
        }

    [download]
    And i want change this foreach loop to for loop it should looks like that? 
    
$arraylenght = lenght($guests);
for($i = 0 ; i < $arraylenght ; $i++)
{
}

    [download]
    Im thinking how i can change this loop foreach to for loop workinkg for this example im trying to do this to practise. I was reading abour foreach loop and i think here guests is a array of people and &guest are one person from this array. Is it maybe possible to do something like this? 
    $arraylenght = lenght($guests);
for($i = 0 ; i < $arraylenght ; $i++)
{
if($guest->{'ident'} =~ /^1[014689]*7[014689]*5[014689]*3[014689]*2[01
+4689]*$/)
            {
                 mywrite($guest);  #my print function
                  
            }
}

    [download]
[reply]
[d/l]
[select]

      This is how you would write it as a C-style for loop:

      for (my $i=0; $i <= $#people; $i++) {
    if($people[$i]{'ident'} =~ /^1[014689]*7[014689]*5[014689]*3[01468
+9]*2[014689]*$/) {
          mywrite($people[$i]);  #my print function
          
    }
}

      [download]

      Comments:

      • @people is an array, and $people[$i] is the element with index $i in that array. The foreach version of the loop automatically maps the current array element to a new variable ($guest in this case) which is nicer to type and read than $people[$i], which is why that kind of loop is usually preferable.

      • $#people is the correct syntax for referring to the last index of the @people array. The length function is only used to get the length of a string, not the number of elements in an array.

      In any case, I strongly recommend that you carefully read through the whole perlintro page (and especially the "Perl variable types" section); it will make learning Perl much easier than trying to figure out the basics by trial-and-error. After that, perlreftut makes for good further reading.

      ---
      Update: Fixed link; thanks taint!

[reply]
[d/l]
[select]
        Did you perhaps mean:

        functions: length EXPR, in your link above, smls? :)

        --Chris

        UPDATE:
        NP smls. I don't even want to count the times I've done it. :)

        ¡λɐp ʇɑəɹ⅁ ɐ əʌɐɥ puɐ ʻꜱdləɥ ꜱᴉɥʇ ədoH

[reply]

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