Computer Programming Concepts and Visual Basic David I. Schneider

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312 Computer Programming Concepts and Visual Basic EXAMPLE 4 The following program uses a second form as a dialog box to total the different sources of income. Initially, only frmIncome is visible. The user types in his or her name and then either can type in the income or click on the command button for assistance in totaling the different sources of income. Clicking on the command button from frmIncome causes frmSources to appear and be active. The user fills in the three text boxes and then clicks on the command button to have the amounts totaled and displayed in the income text box of the first form. Private Sub cmdShowTot_Click() frmSources.Show vbModal End Sub Object Property Setting frmIncome Caption Income lblName Caption Name txtName Text (blank) lblTotal Caption Total Income txtTotal Text (blank) cmdShowTot Caption Determine Total Income Object Property Setting frmSources Caption Sources of Income BorderStyle 3 – Fixed Dialog lblWages Caption Wages txtWages Text (blank) lblInterest Caption Interest Income txtInterest Text (blank) lblDividend Caption Dividend Income txtDividend Text (blank) cmdCompute Caption Compute Total Income Private Sub cmdCompute_Click() Dim sum As Single sum = Val(txtWages.Text) + Val(txtInterest.Text) + Val(txtDividend.Text) frmIncome.txtTotal.Text = FormatCurrency(Str(sum)) frmSources.Hide End Sub [Run, enter name, click the command button, and fill in the sources of income.] All variables declared and general procedures created in the (General) object of a form are local to that form; that is, they are not available to any other form. Such variables and procedures are said to be of form level. However, you can declare global variables and pro-
cedures that are available to all forms. To do so, select Add Module from the Project menu and then double-click on the Module icon. A code window will appear with Module1 in the title bar. Procedures created in this window with the Public keyword will be available to all forms. To declare a variable that is available to all forms, declare it in the Module1 window, but use the word Public instead of Dim. For instance, if the statement Public person As String appears in the Module1 code window, the variable person can be accessed anywhere in the program. The contents of this code window are said to form a (Standard) code module. Project Explorer shows the names of all forms and code modules and gives you access to the code from any form or module. When a code module is selected, you can save it by choosing Save Module As from the File menu. You add an existing code module to a program by choosing Add File from the Project menu. ■ THE COMMON DIALOG CONTROL The common dialog control does not initially appear in your Toolbox. To add the control, select Components from the Project menu, click the Controls tab, and click on the check box to the left of “Microsoft Common Dialog Control 6.0.” Then press the OK button. By convention, names of common dialog boxes have the prefix dlg. The common dialog control can produce each of the useful dialog boxes in Figures 10.13 through 10.17, thereby saving the programmer the trouble of designing custom dialog boxes for these purposes. The common dialog control has no events, only methods and properties. Actually, like the Timer control, the common dialog box control is invisible. However, when you execute a statement of the form CommonDialog1.Show_________ where the blank line is filled with Open, Save, Color, Font, or Printer, the specified dialog box is produced. Table 10.1 gives the purposes of the various dialog boxes. TABLE 10.1 The Different Types of Dialog Boxes Type of Dialog box Purpose of Dialog Box Open Determine what file to open Save As Determine where and with what name to save a file Color Select any available color Font Select a font for the screen or printer Print Help control the printer FIGURE 10-13 An Open Common Dialog Box Five Additional Objects 313
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Computer Programming Concepts and V
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CONTENTS SECTION 1: PROBLEM SOLVING
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13.3 WEB PAGE PROGRAMMING WITH VBSC
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S E C T I O N 1 PROBLEM SOLVING
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4 Computer Programming Concepts and
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10 Computer Programming Concepts an
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S E C T I O N 2 FUNDAMENTALS OF PRO
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3.1 SUB PROCEDURES, PART I Structur
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The second task performed by the ad
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‘The density (number of people pe
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"Hawaii", 1184000, 6471 "Alaska", 6
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dure by just using the variable in
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Call CalculateSum(x, y, s) Call Dis
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■ FORM-LEVEL VARIABLES Visual Bas
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3. In Appendix D, the section “St
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Private Sub cmdDetermine_Click() Di
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Private Sub cmdCompute_Click() Dim
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preceded with the word ByVal. Built
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It is clear from the hierarchy char
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The meaningful procedure names, alo
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FIGURE 3-9 Sample Run for Programmi
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4.1 RELATIONAL AND LOGICAL OPERATOR
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(a) (2 < n) And (n < 6) (b) (2 < n)
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SOLUTION: In the following program,
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The Else part of an If block can be
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picTax.Cls picTax.Print “Your FIC
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Case 4, 5 picOutcome.Print “You a
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EXAMPLE 3 The following program use
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Case Else picResult.Print “The st
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4. The items in the value list must
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The hierarchy chart in Figure 4-4 s
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‘Program to compute employees’
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Private Function TaxMarried(adjPay
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and tells us whether the food meets
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S E C T I O N 5 REPETITION
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132 Computer Programming Concepts a
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S E C T I O N 6 ARRAYS
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S E C T I O N 7 SEQUENTIAL FILES
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S E C T I O N 8 RANDOM-ACCESS FILES
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S E C T I O N 9 THE GRAPHICAL DISPL
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Page 270 and 271: 262 Computer Programming Concepts a
Page 295 and 296: 10.1 LIST BOXES AND COMBO BOXES The
Page 297 and 298: Private Sub cmdAdd_Click() Dim item
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Page 301 and 302: Private Sub cmdDisplay_Click() picF
Page 303 and 304: clicks on the square to toggle betw
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Page 307 and 308: hsbBar.Value changes accordingly. T
Page 309 and 310: THE SHAPE CONTROL The shape control
Page 311 and 312: FIGURE 10-9 A Picture Created with
Page 313 and 314: Rows 9 ScrollBars 0 - flexScrollBar
Page 315 and 316: Private Sub cmdQuit_Click() End End
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Page 319: Clipboard.Clear deletes the content
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Page 333 and 334: 9. Click on the down arrow to the r
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Page 339 and 340: mary key. Databases of student enro
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Page 351 and 352: Creating and Designing Databases 34
Page 353 and 354: 9. When all fields have been specif
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Page 357 and 358: TABLE 11.5(B) TABLE 11.5(C) course
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Page 365 and 366: Task Statement Assign a value to a
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SOLUTION: Object Property Setting f
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4. Methods can be either Function o
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‘Student Class (CStudent) Private
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txtFinal.Text = “” picGrades.Pr
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■ EVENTS In the previous section
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frmCircles.ForeColor = vbRed ‘Mak
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Public Function X() As Integer X =
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End Sub Private Sub cmdDropBomb_Cli
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Next i End Sub Public Function Read
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Remove method. The number of object
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S E C T I O N 13 COMMUNICATING WITH
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A P P E N D I C E S
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APPENDIX C VISUAL BASIC STATEMENTS,
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CANCEL The Cancel property provides
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COLS and ROWS The Cols and Rows pro
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DEFINT, DEFLNG, DEFSNG, DEFDBL, DEF
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ENVIRON Visual Basic has an environ
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FONT.ITALIC or FONTITALIC These pro
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yields “1234.”, Format(1234000,
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the length of the string currently
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ISNUMERIC The value of the function
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Unlock statement is used to remove
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Focus Default Default Number First
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OR (Logical Operator) The logical e
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the same as in the original Dimensi
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SECOND The function Second extracts
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STRETCH When the Stretch property o
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UNLOCK The Unlock command is intend
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[COLOR]: Numbers written in base 16
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Appendix D 457
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466 Technology of the Internet D Da
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468 Technology of the Internet Rela
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470 Technology of the Internet 2. D
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SYSTEM REQUIREMENTS CD-ROM INSTRUCT
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Computer Programming Concepts and Visual Basic David I. Schneider

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