The answers given so far all seem overly complex. If the input is an integer less than 2**32 then simply: 
  sub is_power_of_two { not $_[0] & $_[0]-1 }

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--Dave

In reply to Re: How can I tell if a number is a power of 2? by dpuu
in thread How can I tell if a number is a power of 2? by larryk

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