Wednesday, December 2, 2009

Check if the 20th bit of a 32 bit integer is on or off?

AND it with x00001000 and check if its equal to x00001000


if((num & x00001000)==x00001000)



Note that the digits represented here are in hex.


     0      0      0      0      1      0      0      0
                                 ^                    
                                 |

 x0000   0000   0000   0000   0001   0000   0000   0000 = 32 bits

  ^                              ^                    ^
  |                              |                    |

  0th bit                        20th bit             32nd bit

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