How To Find The Leading Number Of Zero's In a Number using C

Question

for example,if i have number 64,then its binary representation would be 0000 0000 0000 0000 0000 0000 0100 0000 so leading number of zero\'s is 25. remember i have to calculate

Answer 1

Because the logarithm base 2 roughly represents the number of bits required to represent a number, it might be useful in the answer:

irb(main):012:0> 31 - (Math::log(64) / Math::log(2)).floor()
=> 25
irb(main):013:0> 31 - (Math::log(65) / Math::log(2)).floor()
=> 25
irb(main):014:0> 31 - (Math::log(127) / Math::log(2)).floor()
=> 25
irb(main):015:0> 31 - (Math::log(128) / Math::log(2)).floor()
=> 24

Of course, one downside to using log(3) is that it is a floating-point routine; there are probably some supremely clever bit-tricks to find the number of leading zero bits in integers, but I can't think of one off the top of my head...