C#: Sum of all prime numbers in an array

Last update on December 20 2024 12:36:48 (UTC/GMT +8 hours)

Write a C# Sharp program that calculates the sum of all prime numbers in an array of numbers.

Sample Data:
({ 7, 5, 85, 9, 11, 23, 18 }) -> 46
({ 200, 300, 250, 151, 162 }) -> 151

Sample Solution-1:

C# Sharp Code:

using System;
using System.Linq;

namespace exercises
{
    class Program
    {
        static void Main(string[] args)
        {
            // Initializing an array of integers
            int[] nums = { 7, 5, 85, 9, 11, 23, 18 };

            // Displaying original array elements using string.Join method
            Console.WriteLine("Original array elements:");
            Console.WriteLine($"{string.Join(", ", nums)}");

            // Finding and displaying the sum of all prime numbers in the array
            Console.WriteLine("Sum of all prime numbers in the said array: " + test(nums));

            // Creating another array of integers
            int[] nums1 = { 200, 300, 250, 151, 162 };
            Console.WriteLine("\nOriginal array elements:");
            Console.WriteLine($"{string.Join(", ", nums1)}");

            // Finding and displaying the sum of all prime numbers in the second array
            Console.WriteLine("Sum of all prime numbers in the said array: " + test(nums1));
        }

        // Method to check if a number is prime and calculate the sum of all prime numbers in the array
        public static int test(int[] arr)
        {
            int result = 0;

            // Loop through each number in the array
            foreach (int number in arr)
            {
                // Check if the number is prime by calling the IsPrime method
                if (IsPrime(number, number / 2))
                {
                    // If the number is prime, add it to the result
                    result += number;
                }
            }
            return result;
        }

        // Method to check if a number is prime using recursion
        static bool IsPrime(int n1, int i)
        {
            if (i == 1)
            {
                // Base case: If i becomes 1, the number is prime, so return true
                return true;
            }
            else
            {
                // If the number is divisible by i, it's not prime; otherwise, recursively call IsPrime with i decremented by 1
                if (n1 % i == 0)
                    return false;
                else
                    return IsPrime(n1, i - 1); // Recursively call IsPrime itself with i decremented by 1
            }
        }
    }
}

Sample Output:

Original array elements:
7, 5, 85, 9, 11, 23, 18
Sum of all prime numbers in the said array: 46

Original array elements:
200, 300, 250, 151, 162
Sum of all prime numbers in the said array: 151

Flowchart:

Sample Solution-2:

C# Sharp Code:

using System;
using System.Linq;

namespace exercises
{
    class Program
    {
        static void Main(string[] args)
        {
            // Initializing an array of integers
            int[] nums = { 7, 5, 85, 9, 11, 23, 18 };

            // Displaying original array elements using string.Join method
            Console.WriteLine("Original array elements:");
            Console.WriteLine($"{string.Join(", ", nums)}");

            // Finding and displaying the sum of all prime numbers in the array
            Console.WriteLine("Sum of all prime numbers in the said array: " + test(nums));

            // Creating another array of integers
            int[] nums1 = { 200, 300, 250, 151, 162 };
            Console.WriteLine("\nOriginal array elements:");
            Console.WriteLine($"{string.Join(", ", nums1)}");

            // Finding and displaying the sum of all prime numbers in the second array
            Console.WriteLine("Sum of all prime numbers in the said array: " + test(nums1));
        }

        // Method to calculate the sum of all prime numbers in the array using LINQ
        public static int test(int[] nums)
        {
            // Using LINQ to filter prime numbers and calculate their sum
            return nums.Where(n => IsPrime(n, n / 2)).Sum();
        }

        // Method to check if a number is prime using recursion
        static bool IsPrime(int n1, int i)
        {
            if (i == 1)
            {
                // Base case: If i becomes 1, the number is prime, so return true
                return true;
            }
            else
            {
                // If the number is divisible by i, it's not prime; otherwise, recursively call IsPrime with i decremented by 1
                if (n1 % i == 0)
                    return false;
                else
                    return IsPrime(n1, i - 1); // Recursively call IsPrime itself with i decremented by 1
            }
        }
    }
}

Sample Output:

Original array elements:
7, 5, 85, 9, 11, 23, 18
Sum of all prime numbers in the said array: 46

Original array elements:
200, 300, 250, 151, 162
Sum of all prime numbers in the said array: 151

Flowchart:

C# Sharp Code Editor:

Contribute your code and comments through Disqus.

Previous C# Sharp Exercise: Check specific digit in an array of numbers.
Next C# Sharp Exercise: Smallest positive which is not present in an array.