A friend of mine who is learning to program in C, was having diffculty in writing a program to find the sum of all the prime numbers between a specified limit (in her case 3-60). I helped her out with the program, and I thought I'll post it here which might help others.

Code: C

/*

** Program to find the sum of all numbers between 3 and 60

** @author : Pradeep

** @date : 11/29/2006

*/

#include <stdio.h>

void main(void)

{

unsigned int i,j,s=0,is_prime;

for(i=3;i<=60;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;

// optionally you can print the prime numbers too

printf("%d ",i);

}

}

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

}