Write a program in C# to find the largest prime among a collection of numbers

Rajnilari2015
Posted by Rajnilari2015 under C# category on | Points: 40 | Views : 222
Let's say that we have a collection of integers as {104723, 104729, 9998,448 }. Objective is to find the largest prime among a collection of numbers. The below program will do so

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
var numberCollection = new List<int>() {104723, 104729, 9998,448 };
var nonPrimeCollection = new List<int>();

for (int j = 0; j < numberCollection.Count; j++)
{
for (int i = 2; i < numberCollection[j]; i++)
{
if (numberCollection[j] % i == 0)
{
nonPrimeCollection.Add(numberCollection[j]);
break;
}
}
}
Console.WriteLine("Largest Prime {0} ", numberCollection.Except(nonPrimeCollection).Max());
Console.ReadKey();
}
}
}


Result
--------
Largest Prime 104729


The outer for loop is looping thru the entire collection. The inner for loop starts at 2 and picks up those elements that are not primes. And then we are finding the numbers which are prime and finally finding the max.

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