Clearly Visual Basic Programming with Visual Basic 2008
Clearly Visual Basic: Programming with Visual Basic 2008 Chapter 14 Do It, Then Ask Permission
Objectives • Write a posttest loop using the Do…Loop statement • Show a posttest loop in both pseudocode and a flowchart • Concatenate strings Clearly Visual Basic: Programming with Visual Basic 2008 2
Testing after the Fact • Instructions in a pretest loop – May never be processed • Instructions in a posttest loop – Will be processed at least once • Figure 14 -1 – Shows the problem specification and algorithms Clearly Visual Basic: Programming with Visual Basic 2008 3
Clearly Visual Basic: Programming with Visual Basic 2008 4
Clearly Visual Basic: Programming with Visual Basic 2008 5
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More on the Do … Loop Statement • Pretest syntax – The {While | Until} condition section • Part of the Do clause • Indicates that the condition is evaluated before the loop instructions are processed • Posttest syntax – The {While | Until} condition section • Part of the Loop clause • Indicates that the condition is evaluated after the loop instructions are processed Clearly Visual Basic: Programming with Visual Basic 2008 8
Clearly Visual Basic: Programming with Visual Basic 2008 9
Pseudocode and Flowchart for a Posttest Loop • Figure 14 -4 – Shows the pseudocode and flowchart for Example 2 in Figure 14 -3 • The repetition diamond – Appears at the bottom of the loop in a posttest loop Clearly Visual Basic: Programming with Visual Basic 2008 10
Clearly Visual Basic: Programming with Visual Basic 2008 11
The Good Morning Application • Figure 14 -5 – Shows the interface for the Good Morning application • Figure 14 -6 – Shows each message on a separate line in the control • Figure 14 -7 – Shows the pretest and posttest loops in the Good Morning application – Describes the way the computer processes the code in each loop when the user enters the number 0 Clearly Visual Basic: Programming with Visual Basic 2008 12
Clearly Visual Basic: Programming with Visual Basic 2008 13
Clearly Visual Basic: Programming with Visual Basic 2008 14
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Clearly Visual Basic: Programming with Visual Basic 2008 16
But They Said There Were No Strings Attached • Concatenation operator – The ampersand (&) – Used to concatenate (connect or link) strings together • Control. Chars. New. Line constant – Represents the Enter key on your keyboard – Used to create a new line Clearly Visual Basic: Programming with Visual Basic 2008 17
Clearly Visual Basic: Programming with Visual Basic 2008 18
Summary • Instructions in a posttest loop – Will be processed at least once • Do…Loop statement – Used to code a posttest loop • To concatenate strings – Use the concatenation operator: ampersand (&) • Enter key – Represented by the Control. Chars. New. Line constant Clearly Visual Basic: Programming with Visual Basic 2008 19
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