Primes-C

Primes in C

#include <stdio.h>

int main(){

int primesupto = 100;
int i,j;
int isprime = 1;

    for (i=2; i<primesupto; i++){
        for (j=2; j<i/2; j++){    
            if (i%j==0) isprime = 0;
        }
    if (isprime == 1)       printf("%i \n",i);
    isprime = 1;
    }
}

isprime is an int as no Boolean in C

i/2 could be replaced by sqrt(i) but: \

• needs #include <math.h> \
• i,j as double \
• i%j becomes fmod(i,j) \
• "%i \n",i becomes "%i \n",(int)i

Benchmark:

time python primes.py

time ./a.out