For the benefit of others that may want a solution to the problem you initially state, consider using the bi-stable/flip-flop operator:

while ($looping) {
   do_something if condition_one .. condition_two;
}
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Example:

while (<DATA>) {
   print if /two/ .. /four/;
}

__DATA__
line one
line two
line three
line four
line five
[download]

This would print out lines 2, 3 and 4.

See perlop.