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Summation_of_primes.java
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Summation_of_primes.java
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import java.math.BigInteger;
public class Summation_of_primes
{
/*This class finds the sum of all the prime numbers less than LIMIT
*/
public static boolean isPrime(long num)
{
/** This method returns true if a number is prime and false otherwise
@param num the number to be tested
@returns boolean
*/
long limit = (long)Math.sqrt(num);
boolean prime = true;
for (int i=2; i<=limit; i++)
if ((prime == true) && (num%i == 0))
prime = false;
return prime;
}
public static long find_next_prime(long num)
{
/** This method returns the next prime number which is greater than num
@param num the current prime number
@return long
*/
num++;
while (isPrime(num) == false)
num++;
return num;
}
//Usage: arg[0] is the limit
public static void main(String [] args)
{
long first = 2;
long sum = 0;
final int LIMIT = Integer.parseInt(args[0]);
while (first < LIMIT)
{
sum = sum + first;
first = find_next_prime(first);
System.out.println("Prime is:\t" + first + ", The sum is:\t" + sum);
}
System.out.println("The sum is:\t" + sum);
}
}