Computer Programming Concepts and Visual Basic David I. Schneider

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304 Computer Programming Concepts and Visual Basic FIGURE 10-10 A Simple FlexGrid Control The width, measured in twips (there are about 1440 twips to an inch), of each column can be specified only at run time with the ColWidth property. A typical statement is msgFlex.ColWidth(3) = 1200, which sets the width of column 3 to 1200 twips. (The default column width is 555 twips.) Similarly, the RowHeight property specifies the height of each row. The width and height of the entire grid can be specified at design time by dragging the mouse or by setting the Width and Height properties. The grayed row and column in Figure 10-10 are referred to as fixed. Fixed rows and columns must be at the top and left sides of the grid. The number of fixed rows and columns is specified by the FixedRows and FixedCols properties. The grid in Figure 10-10 has the default settings FixedRows = 1 and FixedCols = 1. If the width of the grid is too small to show all the columns, a horizontal scroll bar will automatically appear across the bottom of the grid. Then, during run time, the nonfixed columns can be scrolled to reveal the hidden columns. Similarly, a vertical scroll bar appears when the height of the grid is too small to show all the rows. Scroll bars can be suppressed by setting the ScrollBars property of the grid to 0 – flexScrollBarNone. (The default value of the ScrollBars property is 3 – flexScrollBarBoth.) The individual small rectangles are called cells. Each cell is identified by its row and column numbers. At any time, one cell is singled out as the current cell. Initially, the cell in row 1, column 1 is the current cell. The pair of statements msgFlex.Row = m, msgFlex.Col = n set the current cell to the cell in the mth row and nth column. When the user clicks on a nonfixed cell, it becomes the current cell. The cell’s border becomes dotted, its row number is assigned to the Row property, and its column number is assigned to the Col property. (In Figure 10-10 the cell in row 2, column 4 is the current cell.) The horizontal and vertical lines forming the cells can be turned off by setting the GridLines property to 0 – flexGridNone. Unfortunately, you can’t just place text into a cell by clicking on the cell and typing, as you would with a text box. The statement msgFlex.Text = str places the value of str into the current cell and the statement str = msgFlex.Text reads the contents of the current cell. The text inside all the nonfixed cells of column n can be displayed left-aligned, right-aligned, or centered with a statement of the form msgFlex.ColAlignment(n) = r, where r is 1 for leftalignment, 7 for right-alignment, and 4 for centered. The fixed cells of column n can be justified with a statement of the form msgFlex.FixedAlignment(n) = r. EXAMPLE 1 The following program uses a grid to display an improved version of the table of student expenses from Example 5 of Section 2.5. The five expense categories and numeric data for the table are stored in the sequential file STCOSTS.TXT. Each record of the file consists of a string followed by four numbers. Object Property Setting frmCosts Caption Average Expenses of Commuter Students (1995–96) msgCosts BorderStyle 0 – flexBorderNone Cols 5 FixedCols 0 FixedRows 0 Font Courier New GridLines 0 – flexGridNone
Rows 9 ScrollBars 0 – flexScrollBarNone Private Sub Form_Load() Dim rowNum As Integer, colNum As Integer Dim strData As String, numData As Single ‘Column headings msgCosts.Row = 0 msgCosts.Col = 1 msgCosts.Text = “Pb 2-yr” msgCosts.Col = 2 msgCosts.Text = “Pr 2-yr” msgCosts.Col = 3 msgCosts.Text = “Pb 4-yr” msgCosts.Col = 4 msgCosts.Text = “Pr 4-yr” ‘Read data from data file and obtain column totals Dim total(1 To 4) As Single Open “STCOSTS.TXT” For Input As #1 For rowNum = 2 To 6 ‘row 0 holds headings, row 1 is blank For colNum = 0 To 4 msgCosts.Row = rowNum msgCosts.Col = colNum If colNum = 0 Then Input #1, strData msgCosts.Text = strData Else Input #1, numData msgCosts.Text = FormatCurrency(numData, 0) total(colNum) = total(colNum) + numData End If Next colNum Next rowNum ‘Display totals msgCosts.Row = 8 msgCosts.Col = 0 msgCosts.Text = “Total” For colNum = 1 To 4 msgCosts.Col = colNum msgCosts.Row = 7 msgCosts.Text = “—————” msgCosts.Row = 8 msgCosts.Text = FormatCurrency(total(colNum), 0) Next colNum ‘Set column widths to accommodate data; right-justify dollar amounts msgCosts.ColWidth(0) = 2000 ‘Space for category names msgCosts.ColAlignment(0) = 1 ‘Left alignment For colNum = 1 To 4 msgCosts.ColWidth(colNum) = 1200 ‘Space for dollar amounts msgCosts.ColAlignment(colNum) = 7 ‘Right alignment Next colNum ‘Set overall grid size to minimum needed for the data msgCosts.Width = 2000 + 4 * 1200 msgCosts.Height = 9 * msgCosts.RowHeight(0) End Sub [Run] Five Additional Objects 305
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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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Page 265: S E C T I O N 9 THE GRAPHICAL DISPL
Page 295 and 296: 10.1 LIST BOXES AND COMBO BOXES The
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Page 309 and 310: THE SHAPE CONTROL The shape control
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Page 315 and 316: Private Sub cmdQuit_Click() End End
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12.1 CLASSES AND OBJECTS noun A wor
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Task Statement Assign a value to a
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EXAMPLE 1 and then an instance of t
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[Run, enter the data for a student
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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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