Do...Loop
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This document discusses the Do...Loop statement in Visual Basic, which allows executing a block of code an indefinite number of times until a condition is met. There are two main variations: the Do While loop, which tests the condition before executing the code block, and the Do Loop While loop, which executes the code block first and then tests the condition. Examples are provided to illustrate each using a loop that adds values to a sum variable until it reaches a threshold. Key terms like Do, While, Until, and Loop are also defined.
Do...Loop
- 1. GROUP 1 PRESENTS D …L P
- 2. USE Use a Do…Loop to execute a block of statements an indefinite number of times. There are several variations of the Do...Loop statement, but each evaluates a numeric condition to determine whether to continue execution. As with If...Then, the condition must be a value or expression that evaluates to False (zero) or to True (nonzero). Do…Loop }
- 3. In the following Do...Loop, the statements execute as long as the condition is True: Do While condition statements Loop When Visual Basic executes this Do…Loop, it first tests condition. If condition is False (zero), it skips past all the statements. If it's True (nonzero), Visual Basic executes the statements and then goes back to the Do…While statement and tests the condition again. Example : Dim sum As Integer = 0 Dim counter As Integer = 0 Do While sum < 100 sum = sum + CInt(Textbox1.Text) counter = counter + 1 Loop MsgBox("The loop has run " & CStr(counter) & " times!")
- 4. Another variation of the Do...Loop statement executes the statements first and then tests condition after each execution. This variation guarantees at least one execution of statements: Do statements Loop While condition Example : Dim sum As Integer = 0 Dim counter As Integer = 0 Do sum = sum + CInt(Textbox1.Text) counter = counter + 1 Loop While sum < 100 MsgBox("The loop has run " & CStr(counter) & " times!")
- 5. Term Definition Do Starts the definition of the Do loop. While Repeat the loop until condition is False. Until Repeat the loop until condition is True. condition Boolean expression. If condition is Nothing, Visual Basic treats it as False. statements One or more statements that are repeated while, or until, condition is True. Continue Do Transfers control to the next iteration of the Do loop. Exit Do Transfers control out of the Do loop. Loop Terminates the definition of the Do loop. You can use either While or Until to specify condition, but not both.
- 6. * The above example will keep on adding until counter > 1000. The above example can be rewritten as : Do while counter <= 1000 num.Text = counter counter = counter + 1 Loop Example : Do num.Text = counter counter = counter + 1 Loop Until counter > 1000
- 7. THANK YOU