Description:
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Something wrong with result array from unpack.

var_dump prints correct content.
But when I try to access directly to index, that reports "undefined offset".

Reproduce code:
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$a=unpack('C3',pack("H6","123456"));
var_dump($a);

$k=array_keys($a);
var_dump($k);

$i=$k[0];

print $a[$i];



Expected result:
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Expected result of line 9 is:
18

Actual result:
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Undefined offset:  1 in 1.php on line 9