C: How to find sum of all prime numbers between two nos (both inclusive)?

Question

How to find prime numbers between given intervals? Sample code along with the complexity would be helpful?

Answer 1

 void main(void)
 {
     unsigned int a=100, b=500; // a and b are the two numbers...
     unsigned int i,j,s=0,is_prime;

     for(i=a;i<=b;i++)
     {
         is_prime = 1; // Assuming that current value of i is prime

         // Checking for prime
         for(j=2;j<=(i/2);j++)
         {
             if(i%j==0) // Not prime, set is_prime to 0 and break
             {
                 is_prime = 0;
                 break;
             }
         }

         if(is_prime) // If the number is prime, sum it up
         {
             s += i;
         }
     }

     printf("\n\nThe sum of the prime numbers = %d",s);
 }