Prime Number Algorithm

Question

Can anyone tell me how to implement Sieve of Eratosthenes algorithm in C? I need to generate prime numbers but my algorithm is slow.

My code:

#inclu         


        

Answer 1

In my opinion, your algorithm slow because you calculate the inessential number. try this code

int isPrime(int number){

    if(number < 2) return 0;
    if(number == 2) return 1;
    if(number % 2 == 0) return 0;
    for(int i=3; (i*i)<=number; i+=2){
        if(number % i == 0 ) return 0;
    }
    return 1;

}