LINQ Cookbook, Recipe 3: Find all the prime numbers in a given range (Jonathan Aneja)
Ingredients:
- Visual Studio 2008 (Beta2 or Higher)
Categories: LINQ-To-Objects
Instructions:
- Open Visual Studio 2008, and Click ‘File/New Project’. Find and double-click the ‘Console Application’ Icon
- Add the following code:
Module Module1
Sub Main()
Dim primes = GetPrimesInRange(30, 50)
For Each n In primes
Console.WriteLine(n)
Next
Console.ReadLine()
End Sub
Function GetPrimesInRange(ByVal low, ByVal high) As IEnumerable(Of Integer)
Dim range = Enumerable.Range(1, high)
Return From num In range _
From num2 In range _
Where num Mod num2 = 0 _
Group By num Into Count() _
Where Count = 2 And num > low _
Select num
End Function
End Module
- The grouping is used to select only those numbers that have exactly two factors (i.e. they're prime)
