Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 1

Testing for Valid Numeric Input Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 2

Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 3

Create a project including the form below. Name the text box, txtTest. Code the Exit button. Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.Slide 4

Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 5

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Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 11

An Exception is an Object with Properties Methods Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.12

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Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 14

Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 15

Practice Exercise Create a project that will allow you to test the code on Slide 14. The code should be activated when a button is clicked. What is accomplished by the last argument of MessageBox.Show, ex.GetType.ToString? Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.16

Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 17

Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 18

Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 19

Convert Class vs. Conversion Functions CInt(10.5) rounds to 10 – always rounds Convert.ToInt32(10.5) – throws a Format Exception Which do you want? CInt(x) – throws an Invalid Cast Exception Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.20

Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 21

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Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 30

Do #1-4 on page 221 Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.31

Data Validation: Three Common Types Did the user enter anything? Did the entry convert to the required data type? Was the entry within the required range? Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.32

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Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 36

Data Validation for All User Input Code for all three common checks for every textbox Is there an easier method? Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.37

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Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc. Slide 45

To Learn More: Do p. 221 Exercise 7-1 #1-7 (In #5, use only a single Return statement.) Do p. 222 Exercise 7-2 #1-7 Murach’s Visual Basic 2008, C7, modified or added© 2008, Mike Murach & Associates, Inc.46