This is actually pretty close to what you wanted. Un-comment use warnings and the resulting message will help to identify the problem:

Use of uninitialized value in concatenation (.) or string at first.pl 
+line 5.

[download]

The problem loop is:

foreach my $num (@arr) {
        print "Index is: $num. Value is: $arr[$num] ";
}

[download]

and as the output shows, the loop value is always one greater than the index. That’s because arrays in Perl (as in C) are subscripted starting from zero, so $arr[1] is actually the second element. The loop is easily fixed:

foreach my $num (@arr) {
        print "Index is: $num. Value is: $arr[$num - 1] ";    # Subtra
+ct 1 from the index
}

[download]

Also un-comment use strict, and you’ll see that the only error message pertains to this line:

for($num = 0; $num<= $#arr;$num++) {

[download]

Declare $num as a lexical variable:

for (my $num = 0; ...

[download]

and strict is happy.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re^2: Good Perl book? by Athanasius
in thread Good Perl book? 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":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.