June 2018 Update

Task/Extensible-prime-generator/VBA/extensible-prime-generator.vba

@@ -0,0 +1,74 @@
+Option Explicit
+
+Sub Main()
+Dim Primes() As Long, n As Long, temp$
+Dim t As Single
+    t = Timer
+
+    n = 133218295 'limit for an Array of Longs with VBA on my computer
+    Primes = ListPrimes(n)
+    Debug.Print "For N = " & Format(n, "#,##0") & ", execution time : " & _
+        Format(Timer - t, "0.000 s") & ", " & _
+        Format(UBound(Primes) + 1, "#,##0") & " primes numbers."
+
+    'First twenty primes
+    For n = 0 To 19
+        temp = temp & ", " & Primes(n)
+    Next
+    Debug.Print "First twenty primes : "; Mid(temp, 3)
+    'Primes between 100 and 150
+    n = 0: temp = vbNullString
+    Do While Primes(n) < 100
+        n = n + 1
+    Loop
+    Do While Primes(n) < 150
+        temp = temp & ", " & Primes(n)
+        n = n + 1
+    Loop
+    Debug.Print "Primes between 100 and 150 : " & Mid(temp, 3)
+    'Number of primes between 7,700 and 8,000
+    Dim ccount As Long
+    n = 0
+    Do While Primes(n) < 7700
+        n = n + 1
+    Loop
+    Do While Primes(n) < 8000
+        ccount = ccount + 1
+        n = n + 1
+    Loop
+    Debug.Print "Number of primes between 7,700 and 8,000 : " & ccount
+    'The 10 x Xth prime
+    n = 1
+    Do While n <= 100000
+        n = n * 10
+        Debug.Print "The " & n & "th prime: "; Format(Primes(n - 1), "#,##0")
+    Loop
+    Debug.Print "VBA has a limit in array's dim"
+    Debug.Print "With my computer, the limit for an array of Long is : 133 218 295"
+    Debug.Print "The last prime I could find is the : " & _
+        Format(UBound(Primes), "#,##0") & "th, Value : " & _
+        Format(Primes(UBound(Primes)), "#,##0")
+End Sub
+
+Function ListPrimes(MAX As Long) As Long()
+Dim t() As Boolean, L() As Long, c As Long, s As Long, i As Long, j As Long
+    ReDim t(2 To MAX)
+    ReDim L(MAX \ 2)
+    s = Sqr(MAX)
+    For i = 3 To s Step 2
+        If t(i) = False Then
+            For j = i * i To MAX Step i
+                t(j) = True
+            Next
+        End If
+    Next i
+    L(0) = 2
+    For i = 3 To MAX Step 2
+        If t(i) = False Then
+            c = c + 1
+            L(c) = i
+        End If
+    Next i
+    ReDim Preserve L(c)
+    ListPrimes = L
+End Function