No, not at all - Your code will only pass through a single iteration of the loop as on the first pass, the value of $num is added to $num. The result is that $num equals 40 and the while loop is exited. I think you may have been meaning, ignoring formatting syntax errors ...

$num = 20;
while ($num < 30) {
    print "num is $num\n";
    ++$num;
}
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Although, good pick up on the syntax error with the line - $while($num<30){ - Although this had been addressed previously within this thread.

 

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