Question

Determine the output displayed when the button is clicked on.

Private Sub btnDisplay_Click(...) Handles btnDisplay.Click

Dim total As Double = 0

Dim num As Integer = 1

Do While num < 5

total += num

num += 1

Loop

txtOutput.Text = CStr(total)

End Sub

Answer 1

Iteration #1
   num:1
   Total:0
  
   Total is updated as Total += num => Total = 1 + 0 => Total = 1
   num is updated as num += 1 => num = 1 + 1 => num = 2

  
Iteration #2
   num:2
   Total:1

   Total is updated as Total += num => Total = 1 + 2 => Total = 3
   num is updated as num += 1 => num = 2 + 1 => num = 3
  
  
Iteration #3
   num:3
   Total:3

   Total is updated as Total += num => Total = 3 + 3 => Total = 6
   num is updated as num += 1 => num = 3 + 1 => num = 4
  
  
Iteration #4
   num:4
   Total:6
  
   Total is updated as Total += num => Total = 6 + 4 => Total = 10
   num is updated as num += 1 => num = 4 + 1 => num = 5
  
  
When num is 5, Condition num < 5 fails and While loop Iteration stops

Hence the final output will be value 10