Copyright © Don Kussee 1410-Ch4 #521 CNS 1120 Chapter 4 Performing Calculations & Manipulating Data 1120-Ch4.PPT.

Copyright © Don Kussee 1410-Ch4 #52

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CNS 1120Chapter 4

Performing Calculations & Manipulating Data

1120-Ch4.PPT


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Distribution to Non-Visual Basic computers

• You must include DLL's, OCX’s, ActiveX’s• In Professional Version

– Go to VB6.0 Directory– Start “Package & deployment Setup Wizard”

• Could be put as a shortcut on the desktop

• Missile program took 2 disks to store 13 files


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Disk 1


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Disk 2


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Expressions145

• Arithmetic expression result in number– Arithmetic calculations

• String expression result in a string– Manipulate string data4

• Logical expression result in true or false– Choose an action (path) from several choices– Often includes arithmetic & string expressions– False is always 0, true is any non 0 -37 .0006


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Programming Concept words

• Expression - series of numeric/logical/string/operator symbols the computer understand and can process

• Statement - tells the computer to do one or more actions, often includes expressions

• Operator - a symbol that the computer understands means to do some one thing

• Function - a more complex operation


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Relationships

Statement

Expressions

Arithmetic - String - Logical

FunctionsOperators Values

1 or more

0 or more 0 or more 0 or more


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Statements

Dim x As Integer ‘Not an expressionDim s As String ‘Not an expressionx = (((8 + 9)*2)+2)/12 ‘Math expressionx = Sqr(x) ‘Function expressions = “Quick ” & “Fox” ‘String expression• Evaluation of right side is done first• Then assignment to left side occurs 3 = x


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Functions have a return value

• Dim str As String• str = InputBox( “First Name” )• Physically - the whole InputBox term is

replaced by the value that is returned so it becomes

• str = “Don”• then the assignment is made


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Conversion String to Number Functions Val ( )

• Changes from string to a number data type• Val(String) changes a string a number.

Combines over blanks, tabs, LF up to the First non-number character (letter$, -)

• String with no number first gets a value = 0• Number outside acceptable value get Err 6• See also CInt(), CLng(), CSng(), CDbl()


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Conversions Number to String Str$( )

• Changes any numerical data type to a String value (for use using label or textbox). Note this will happen automatically if you don’t force the change. I require you to force the change you want. Most languages do!

• String = Str$(number)• Label1.Caption = Str$(number)


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Computer Terms

• Statement• Evaluation• Binary Operator• Unary Operator• Modulus• Integer division• Scientific notation

• Function• Argument


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Binary Arithmetic Operators

• Addition + 9 = 7 + 2• Subtraction - 5 = 7 - 2• Multiplication * 14 = 7 * 2• Division / 3.5 = 7 / 2• Exponentiation ^ 49 = 7 ^ 2• Integer Division \ 3 = 7 \ 2 • Modulo MOD 1 = 7 MOD 2


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Integer Divisions & Modulus

6.33 638 / 6 6/ 38.00 38 \ 6 6/ 38 -36 -36 20 remainder 2 -18 2 = 38 MOD 6 20 ? = 29 MOD 5 - 18 ? = 16 MOD 12 = 84 MOD 20


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Unary Operators

• Positive + x = + 7• Negative - x = -13• Unary & Binary operators

– x = 7 + -2– x = - (-7 + 13) + (-3 - -4)


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QUIZ

• ? = 22 / 6• ? = 22 \ 6• ? = 13 MOD 4• ? = 64 / 2• ? = 60 \ 21• ? = 56 MOD 2• ? = 12 / 13

• ? = 99 \ 100• ? = 99 / 100• ? = 23 MOD 3• ? = 642 MOD 2• ? = 512 MOD 16• ? = 511 MOD 16• ? = 513 MOD 16


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Scientific or Exponential Notation

• 3.08E+12 = 3080000000000.00• 3.08E-6 = 0.00000308• -4.9E+1 = -49.• ? = 6.8E-3 • ? = 7.99998E+3• ? = 9.999999E-13• ? = 1.8E+308


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Operator Precedence Rule

1 Parenthesis ( )2 Exponential ^3 Unary operators + -4 Mult. & Div. * /5 Integer Division \6 Modulus MOD7 Add & Sub + -8 Concatenation &

9 Comparison = A Comparison < > B Comparison <C Comparison >D Comparison <=E Comparison >=

Z Assignment =


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Operator Precedence Rule

F Unicode String LikeG Object compare IsH Logical NotI Logical AndJ Logical OrK Logical XorL Logical EqvMLogical Imp

Z Assignment =


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Comment’s

• Used to document code– Block comments tell what several lines will do– Comment to tell that line itself Note: Page 161

• REM as the first word in a line of code, causes the computer to ignore the whole line of code

• REM the abbreviated symbol ‘ can be used anywhere with in a line - rest of line ignored


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Some Arithmetic Functions

• Abs ( value ) returns the absolute value• Sgn ( value ) returns the sign of the value• Fix (value) truncates any fractional part• Exp ( value ) converts to Log base e I.e.

7.9048053225245E+206 = Exp( 476.4)• Log ( value ) converts base e number to a

number example 748 = Log(Exp(748))


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Random number Rnd ( )

• Random numbers are often required • Rnd() returns a number v >= 0, v < 1• For a specific number inclusive

1 to 500 v = Fix(500 * Rnd( ))+10 to 299 v = Fix(300 * Rnd( ))17 to 92 v = Fix(75 * Rnd( ))+17

• Randomize ‘ starts Rnd ( ) in different placeuse Randomize only once per program


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Overflow errors - Err 6

• Program stops - error is given• For Integer or Long variables• The memory set aside for a variable will not

hold the number assigned I.e Dim c As Integer c = 33000


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Round off errors, No stop no error but answer can be wrong

• Data types Single or Double does not round• The computer can not store a base 10 value

correctly as a base 2 format number• Data type Currency does round

– x = 4,407,351,698,474.15– Single x = 4,407,351,000,000.00 x 10 12

– Double x = 4,407,351,698,474.10 x 10 12

– Currency x = 4,407,351,698,474.1500


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Conversion from Single & Double to Integer & Long

• Moving from one data type to a other type• Dim C As Integer : Dim D As Single• No error occurs because it is the wrong type,

the number is just adjusted for C = 2.9 the fraction is truncated C = 2 C = 6.999999 C = 6 D = 89 the figure is adjusted to D = 89.0 E = -37 if E of type currency E= -37.0000


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String Operators

• & (or + ) Concatenation operator• Dim a As String• Dim B As String• a = “Tom”• B = “Jones”• lblX.caption = a & B ‘TomJones• lblX.caption= a & “ “ & “Jones” ‘ Tom Jones


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String Comparisons

• ( “Tom Brown” = “Tom brown” )• Strings are compared letter by letter until

– A difference between the ANSI value of the two characters in the same position is found F

– One string ends and the other continues (diff) F– Both strings end with no differences - True

• 32 = Abs(UCase -LCase) • 1, 0, -1 returned by StrComp(Str1, Str2,rule)


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String Comparisons

• Same operators are used• x = 486 = “486Mhertz” ‘ true ? = operator• Auto-conversion of string to get Integer

data type, so problem is now 486 = 486?– Spaces, CrLf, tabs skipped over ‘ 5 9 6=596

• X = 486 = “CPU486” ‘ type mismatch


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String Comparison

• Figure 4-6 on page 175• If ( “Jim B” = “Jim D”) Then• ? If ( “Jim b” > “Jim D”) Then• ? If ( “Jim B” < “Jim D”) Then • ? If ( “Jim Brown” < “Jim D”) Then• ? If ( “7” > “4” ) Then• ? If (“122 main” > “128 main”) Then


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String functions

• Len(Str) ‘Returns number of characters • Val (Str) ‘Ret. Numbers (first) in a string• CDbl(str) ‘ same Val but for international• If the function name ends in $, the the

function returns a string • Str$ (Num ) ‘Number to string characters


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Format ( ) function

• Used to format output for ease of reading• Can format strings or date & time• Will insert $ + 001,987.9700 Format$( )

‘adds $, commas, sign, number of places for numbers or zeros

• Several standard functions available - or can be custom designed


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String functions continued

• Function returns a string then function$• Left$( ) ‘returns left most characters• Right$( ) ‘returns right most characters• Mid$( ) ‘returns middle characters• LCase$( ) ‘Converts upper letters to lower• UCase$( ) ‘Converts lower letters to upper


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String functions continued

• LTrim$( ) ‘Removes leading spaces• RTrim$( ) ‘Removes trailing spaces• Trim$( ) ‘Removes leading & trailing• String$( ) ‘Repeats a character• Asc() ‘Convert character to ANSI value• Chr$( ) ‘Convert ANSI value to character• Instr$( ) ‘Find sub-string in a string


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ASCII - ANSI table - page 175

• Shapes for a code number ? =“a”, ? =“A”, ? =“B”, ? = “2” , ? = “3”, ? = “4”

• Different shape depending on language• Non-printable letters

– Space . tab backspace bell lf ff cr• Carriage return & Line feed - vbCrLF • Vertical tab


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ANSI code comments

• Difference between A and a is 32 65 - 97 = 32• Bell = 7 backspace = 8• Space = 32 a = 97• Period = 46 z = 122• character 1 = 49 A = 65• character 9 = 57 Z = 90


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Unicode

• New code, allows 65,000 different shapes• First 256 values = ANSI code• Japanese, Cyrillic, Arabic characters can be

added• Java uses this code


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TextBox txt

• 52 Properties– Text– Appearance & location– BorderStyle– MaxLength (d=32,000)– MultiLine– ScrollBars– Password– SelLength, SelText

• 23 Events– Change– Click– DragOver– KeyPress

• 11 Methods– Move– Refresh– ZOrder


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TextBox properties

• The TextBox is the preferred input object• Text is the input (& output) property• No Caption Property• Enabled - grayed out, does not work• Visible - can you see it• Locked - can the user change the text• Usual event - Change, Click


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Ok & Cancel Buttons

• Command buttons with Captions• Default = “Hooks” object to the return key• Cancel = “Hooks” object to the Esc key• Enable = False (grayed out, non functional)• Visible = False (not visible on form)


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Logical Expressions

• Results of logical expressions result in a False ( a 0 Value) or True (any non-zero) and is stored as a -1 (Book wrong page 189)

• Binary operators <, <=, >, >=, =, < >• ? = 7 < 9 ? = 6<= 7 ? = 6 < >6• ? = -9 > 7 ? = “day1” > “day2”• ? = -7 > -9 ? = 3 + 7 < 4 + 6


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Assignment Operator Vs Equality Test Operator

• = is The assignment operator, and is a Unary operator (first operator after variable)

• = is an Equality Test operator, but is a Binary operator (not first operator after)– Pascal uses := for assignment, = for test– C, C++, Java use = = for tests, = for assignment– Operator overloading occurs frequently 6 --5– How do we tell between to, two, and too


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Boolean Type Operators

• Not Unary operator• And Binary operator• Or Binary operator• Xor Binary operator• = (“a” > “b”) And (5 = r)• = (7 < 9) Or (6 = 5) Or (Not (7 = 13))• Boolean operators precedence is ????


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And T F

T T F

F F F

Test 1Test 1

And truth table

Test2Test2


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Or truth table

Or T F

T T T

F T F

Test 1Test 1

Test 2Test 2


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Xor truth table

Xor T F

T F T

F T F

Test 1Test 1

Test 2Test 2


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Not unary truth table

Not T F

F T

Test 1Test 1


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Practice

(7 >= 5) Or (P > R) ‘Parentheses not required(Not (6<>8)) And (Not(-7 >-4))(9 MOD 6 < 2 ^ 3) Or (8 \ 3 > 4 ^1/2)

(2 < 3) Or (7 < 8) Or (6 > 3) Or ( -4 < -1)(3>2) And (4<3) Or (-9 <-5)(6>3) And (3>1) And (7>6)(Not(6>3)) And (-7<-3) Xor (6=6)


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Additional functions

• BValue = IsNumeric (variable name) • IsDate( ) IsMissing( ) IsNull( )• IsEmpty( ) IsArray( ) IsError( )

• Ternary Operator - tests first term• IIf (3 < 2 , 2 +3 , 2*3)

returns 2nd term if true, 3rd term if false


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windows Access keys

• A combination of Alt and some other key• Denoted in menus with underlined letter• Hooked up in VB automatically

– Placing a “&” preceding any letter– Unique to a Form– Allowed in Captions

• cmdExit.caption = “E&xit” is displayed as Exit and click event occurs when Alt & X key are pressed.


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Chapter 4 Keywords

• ANSI/ASCII /Unicode• Arithmetic expression• String expression• Logical Expression• Binary Operator• Unary Operator• Ternary Operator• Comparison Operator

• InputBox ( ) function

• Text box control• CarrageReturn/LineFeed• Case of Characters• Concatenation• Function - return value

Copyright © Don Kussee 1410-Ch4 #521 CNS 1120 Chapter 4 Performing Calculations & Manipulating Data 1120-Ch4.PPT.

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