if some kind soul would give an explanation of why the third antirice loop works, i could sleep easy. easier... 

foreach my $key ( @{[%hash]} ) {
 print $key;
 delete $hash{$key};
}

[download]

What antirice has done here is to take a copy of the hash as a list. After this, interating over the copy means that every second delete attempts to delete a key that never existed in the hash and fails quietly while all the others succeed.

No doubt you're confused by the 

@{[%hash]}

[download]
bit.

Enclosing something in square brackets in Perl takes it in list context. It also generates an array reference to that. So %hash here is copied into an annoymous array. This is then deferenced by the @{}s because foreach expects a list, not a reference.

Does this help?

All the best,

jarich

In reply to Explaining @{ [ %hash ] } by jarich
in thread Hashes: Deleting elements while iterating by knexus

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.