sol1.c File Reference

Problem 10 solution More...

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

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Functions
char	is_prime (unsigned long n)
unsigned long long	sum_of_primes (unsigned long N)
int	main (int argc, char *argv[])

Detailed Description

Problem 10 solution

Author

Krishna Vedala

Function Documentation

is_prime()

char is_prime

(

unsigned long

n

)

Function to check if a number is prime

{
    for (unsigned long i = 2; i < sqrtl(n) + 1; i++)
        if (n % i == 0)
            return 0;
 
    return 1;
}

main()

int main	(	int	argc,
		char *	argv[]
	)

Main function

{
    unsigned long n = 100;
 
    if (argc == 2)         /* if command line argument is provided */
        n = atol(argv[1]); /* use that as the upper limit */
 
    printf("%ld: %llu\n", n, sum_of_primes(n));
 
    return 0;
}

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sum_of_primes()

unsigned long long sum_of_primes

(

unsigned long

N

)

Computes sum of prime numbers less than N

{
    unsigned long long sum = 2;
 
    for (long i = 3; i < N; i += 2) /* skip even numbers */
        if (is_prime(i))
            sum += i;
 
    return sum;
}

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