by Waty Thierry (60 Submissions)
Category: Math/Dates
Compatability: Visual Basic 4.0 (32-bit)
Difficulty: Unknown Difficulty
Originally Published: Tue 13th April 1999
Date Added: Mon 8th February 2021
Rating: 
(1 Votes)
Returns true if the number is a prime number
VBcoders
Returns true if the number is a prime number.
false if it is not.
This should work reasonably well for small
numbers (32-bits or less). For larger numbers
the Rabin-Miller test should be used.
Public Function IsPrime(ByVal n As Long) As Boolean
Dim i As Long
IsPrime = False
If n <> 2 And (n And 1) = 0 Then Exit Function test if div 2
If n <> 3 And n Mod 3 = 0 Then Exit Function test if div 3
If n <> 5 And n Mod 5 = 0 Then Exit Function test if div 5
For i = 6 To Sqr(n) Step 6
If n Mod (i - 1) = 0 Then Exit Function
If n Mod (i + 1) = 0 Then Exit Function
Next
IsPrime = True
End Function
