C Programming - Is that a Prime Number?

Interviewers favourite :)The problem is to find out whether a number is prime or not?

This is the one best solution that I could find out!!!

Solution:

/* returns 1, if number is prime else 0 */

int prime(int number)

{

int iter,bound;

if (!(number % 2)) return (number == 2);

if (!(number % 3)) return (number == 3);

if (!(number % 5)) return (number == 5);

for(iter = 7; (iter * iter)<= number; iter += 2)

if ( number % iter == 0 )

return 0;

return 1;

}

Labels: C

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