They differ in precedence, and are otherwise the same. This means that if you write:

$a=$b || $c;
$a=$b or $c;
[download]

Perl evaluates this:

$a=($b || $c);
($a=$b) or $c;
[download]

This changes what gets assigned to $a, and can also change the context of a statement (from perlop):

@info = stat($file) || die;     # oops, scalar sense of stat!
@info = stat($file) or die;     # better, now @info gets its due
[download]

This occurs because die is in scalar context, (so || is great for obfuscation!). || is also appropriate where you want to cause the rightmost value to get assigned. That is:

$a=$b || $c
[download]

Would assign $c to $a if $b was false, otherwise it would assign $b to $a. Whereas:

$a=$b or $c
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Would not assign $c to $a when $b was false! In scalar context, using || for dieing is fine, but you'll run into trouble with things where context is important. or is almost always what you mean in these cases.

If you still don't believe me, try this:

$a=0 or 1;
$b=0 || 1;
[download]

$a will be 0, and $b will be 1.

Andrew.



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