Recursion: 4 ways to get it working

[bplus]

Here is a Checkerboard fresh from my brain and QB64 IDE:

Code: (Select All)

_Title "Checkerboard by recursion" ' b+ 2023-02-17
' 8 X 80 = 640
Screen _NewImage(640, 640, 12) ' use 16 QB colors
Check 1, 1
Sleep
Sub Check (x, y)
    If (y Mod 2) Then
        If x Mod 2 Then c = 4 Else c = 0
    Else
        If x Mod 2 Then c = 0 Else c = 4
    End If
    Line ((x - 1) * 80, (y - 1) * 80)-Step(80, 80), c, BF
    Line ((x - 1) * 80, (y - 1) * 80)-Step(79, 79), 14, B
    x = x + 1
    If x > 8 Then y = y + 1: x = 1
    If y > 8 Then
        Exit Sub
    Else
        Check x, y
    End If
End Sub