# VB.NET - Code Samples - Find Prime Numbers Algorithm

## VB.NET Prime Number Searching

### Synopsis:

This is an algorithm created for a contest on vbforums.com . Pass the function the number of primes you want to generate and it will return them as an int32 array.

### The Code:

Private Function GeneratePrimeList2(ByVal numOfPrimes As Int32) As Int32() Dim primes(numOfPrimes - 1) As Int32 Dim cntr As Int32 = 5 Dim pcntr As Int32 = 2 Dim i As Int32 Dim maxPrimeSqrRoot As Double primes(0) = 2 primes(1) = 3 Do Until pcntr = numOfPrimes 'get the highest factor to check against if under the 'predetermined maximum maxPrimeSqrRoot = Math.Sqrt(cntr) 'for each prime other than two For i = 1 To pcntr - 1 'check for clean division If cntr Mod primes(i) = 0 Then 'not prime Exit For Else 'if all primes up to maxfactor used or all primes used then it is prime If primes(i + 1) > maxPrimeSqrRoot OrElse i = pcntr - 1 Then primes(pcntr) = cntr pcntr += 1 Exit For End If End If Next cntr += 2 Loop Return primes End Function