To "easily find out the place where unpack() finished" you could simply consume the string as you go: 
(my($t),$foo) = unpack('Ca*', $foo);
if ( $t == 3 ) {
  ($v,$foo) = unpack('Z*a*', $foo); 
}

[download]
Unforunately Z* doesn't finish at the zero byte - it actually consumes the remainder of the input and discards everything beyond the zero.

In reply to Re: How much was unpack()ed? by Anonymous Monk
in thread How much was unpack()ed? by Stevie-O

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