For…Next

Best when you know the exact iteration count. Supports positive/negative Step.

For i As Integer = 1 To 10
    Console.WriteLine(i)
Next

For i As Integer = 10 To 1 Step -1
    Console.WriteLine(i)
Next

Flow (mental model)

• Init counter → i = start
• Check boundary → i <= end?
• If True → run body → i += Step → repeat
• If False → exit loop

For Each…Next

Iterate collections and arrays. The iteration variable is read‑only.

Dim fruits As String() = {"Apple", "Banana", "Cherry"}
For Each fruit As String In fruits
    Console.WriteLine(fruit)
Next

Dim nums As New List(Of Integer)({1,2,3,4})
For Each n In nums
    Console.WriteLine(n)
Next

Flow

• Get enumerator → MoveNext()
• If True → Current item → body
• Repeat until MoveNext() returns False

Dim numbers = {1,2,3,4,5}
numbers.ToList().ForEach(Sub(n) Console.WriteLine(n))

Do While / Do Until (pre‑check)

Condition is checked first. May execute the body zero or more times.

Dim c As Integer = 0
Do While c < 5
    Console.WriteLine(c)
    c += 1
Loop

Dim c As Integer = 0
Do Until c >= 5
    Console.WriteLine