What is the fastest way to find if a number is even or odd?

Asked 2010-02-09T12:55:24.147

c micro-optimization

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3 Answers

int i=5;
if ( i%2 == 0 )
{
   // Even
} else {
   // Odd
}

answered 2010-02-09T12:57:18.897

Check to see if the last bit is 1.

int is_odd(int num) {
  return num & 1;
}

answered 2010-02-09T12:59:17.783

Check the least significant bit:

if (number & 0x01) {
  // It's odd
} else {
  // It's even
}

answered 2010-02-09T12:59:43.897