Introduction to Computing Dr. Nadeem A Khan. Lecture 11.

Introduction to Introduction to ComputingComputing

Dr. Nadeem A KhanDr. Nadeem A Khan

Lecture 11Lecture 11

Data Types !Data Types !

► For Strings:For Strings:

Variable-Length StringVariable-Length String

Fixed-Length Strings Fixed-Length Strings

Data TypesData Types

► For Numbers (Whole numbers or not):For Numbers (Whole numbers or not):

Single (Precision Floating Point)Single (Precision Floating Point)

Double (Precision Floating Point)Double (Precision Floating Point)

Currency Currency

Data Types Data Types (Contd.)(Contd.)

► For Numbers (Whole numbers only):For Numbers (Whole numbers only):

IntegerInteger

Long (Integer)Long (Integer)

Byte Byte


► For Boolean values: For Boolean values:

BooleanBoolean


► Use Letters, digits and underscores onlyUse Letters, digits and underscores only No predefined keywords (integer, single, Dim etc.)No predefined keywords (integer, single, Dim etc.)

► Max. length: 255 chars. (Min. length: 1 char.)Max. length: 255 chars. (Min. length: 1 char.)

► Begin with a letter (e.g. a, A)Begin with a letter (e.g. a, A)

► Case-Case-InInsensitive (Game=GAME=gAme)sensitive (Game=GAME=gAme)

Variable NamesVariable Names

►Use meaningful namesUse meaningful names

►Good to follow the naming Good to follow the naming conventionsconventions

e.g:e.g:

totaltotal

numberOfCarsnumberOfCars

Variable Names Variable Names (Contd.)(Contd.)

Converting Data Converting Data Types !Types !

►Already know:Already know:

ValVal

Str$Str$

Conversion functionsConversion functions

► Conversion FunctionsConversion Functions Converts toConverts to CboolCbool BooleanBoolean CbyteCbyte ByteByte CcurCcur CurrencyCurrency CDblCDbl DoubleDouble CintCint IntegerInteger CLngCLng LongLong CsngCsng SingleSingle CstrCstr StringString

Conversion functions Conversion functions (Contd.)(Contd.)

► Converts the input value to a specific data Converts the input value to a specific data

typetype

► Only convert those input values that are Only convert those input values that are appropriateappropriate

for that data type for that data type

Conversion functions Conversion functions (Contd.)(Contd.)

Using commas: ExampleUsing commas: Example

►Picture1.Print “North”, “to”, “the”, Picture1.Print “North”, “to”, “the”, “future”“future”

►Picture1.Print “No:”, 6, Picture1.Print “No:”, 6,

More on Print methodMore on Print method

Using commas: ResultUsing commas: Result

►North North to to the the futurefuture

►No:No: 6 6 (‘6’ displayed 1 pos. (‘6’ displayed 1 pos. further further in zone) in zone)

More on Print method More on Print method (Contd.)(Contd.)

Using commas: RulesUsing commas: Rules

►Line of a Picture Box divided in zonesLine of a Picture Box divided in zones

►A Zone: 14 positionsA Zone: 14 positions

►Print Items displayed in consecutive Print Items displayed in consecutive zones zones


Using the Tab function: ExampleUsing the Tab function: Example

► Picture1.Print “Hello”;Tab(10); “World”; Picture1.Print “Hello”;Tab(10); “World”; Tab(20);”!”Tab(20);”!”

► Picture1.Print “No:”;Tab(5);5Picture1.Print “No:”;Tab(5);5


Using the Tab function: ResultUsing the Tab function: Result

►HelloHello WorldWorld !! (‘World’ at 10th (‘World’ at 10th position)position)

(‘!’ at 20th position)(‘!’ at 20th position)

►No: 5 No: 5 (‘5’ at 6th position)(‘5’ at 6th position)


Using the Tab functions: RulesUsing the Tab functions: Rules

► Tab(n); (where n is a positive integer)Tab(n); (where n is a positive integer)

=>Following Item (if possible) displayed =>Following Item (if possible) displayed beginning at the nth position of the line beginning at the nth position of the line


Using the Spc function: ExampleUsing the Spc function: Example

►Picture1.Print “Hello”;Spc(3); “World”Picture1.Print “Hello”;Spc(3); “World”

►Picture1.Print “No:”;Spc(3);5 Picture1.Print “No:”;Spc(3);5


Using the Spc function: ResultUsing the Spc function: Result

►Hello WorldHello World (“World” after 3 (“World” after 3 spaces)spaces)

►No: 5 No: 5 (“5” after 4 (“5” after 4 spaces)spaces)


Using the Spc functions: RulesUsing the Spc functions: Rules

►Spc(n); (where n is a positive integer)Spc(n); (where n is a positive integer)

=>Following Item printed after n spaces =>Following Item printed after n spaces


Output to the Printer:Output to the Printer:

►Printer.Print Printer.Print exprexpr

=>sends expression =>sends expression exprexpr to the printer to the printer

=>works the same way as =>works the same way as Picture1.PrintPicture1.Print



Let Printer.FontName = “Script”Let Printer.FontName = “Script”Let Printer.FontBold = TrueLet Printer.FontBold = TrueLet Printer.FontSize = 12Let Printer.FontSize = 12

=> set properties => set properties



►Printer.NewPage Printer.NewPage (new page)(new page)►Printer.EndDoc Printer.EndDoc (document (document

ended)ended)►PrintForm (performs the screen PrintForm (performs the screen

dump)dump)


►MsgBox MsgBox messagemessage, , “, , “CaptionCaption””

► A Message Box will appearA Message Box will appear displaying the string displaying the string messagemessage ‘‘Caption’Caption’ will appear in the title bar will appear in the title bar

The Message Box for OutputThe Message Box for Output

►Let Let stringVarstringVar = InputBox$( = InputBox$(messagemessage))

► =>An InputBox will appear =>An InputBox will appear displaying the string displaying the string message; message; Assigns Assigns the typed user response to the typed user response to stringVarstringVar after Enter is pressed or OK is clickedafter Enter is pressed or OK is clicked

The Input Box for InputThe Input Box for Input

► Open “Open “filespecfilespec” For Input As #” For Input As #nn

Opens a file for reading and assigns the reference Opens a file for reading and assigns the reference number number nn

► Input #Input #nn, , varvar Next available item is read from the file and Next available item is read from the file and

assigned to variable assigned to variable varvar

► Close #Close #nn Closes the file Closes the file

Reading Data from File Reading Data from File

► DATA.TXT file has two lines:DATA.TXT file has two lines:““September”September”

2626

=> items separated by commas or line-breaks;=> items separated by commas or line-breaks;

data item of same type as the data to bedata item of same type as the data to be

assigned to the corresponding variableassigned to the corresponding variable

Reading Data from File Reading Data from File (Contd.)(Contd.)

Example:Example:

Sub Command1_Click()Sub Command1_Click()Dim month As String, date As SingleDim month As String, date As SinglePicture1.ClsPicture1.ClsOpen “DATA.TXT” For Input As #1Open “DATA.TXT” For Input As #1Input #1, monthInput #1, monthInput #1, dateInput #1, datePicture1.Print “ Today is ”; month; datePicture1.Print “ Today is ”; month; dateClose #1Close #1

End SubEnd Sub


The result:The result:

Today is September 26 Today is September 26


► Rem Rem texttext ► ……………… ……………….. ‘.. ‘texttext

e.g:e.g:

Rem Compute weekly payRem Compute weekly pay

Dim hrs as Single ‘hours worked Dim hrs as Single ‘hours worked

Inclusion of CommentsInclusion of Comments

Reading for today Reading for today

►Schneider: Section 3.5Schneider: Section 3.5

Introduction to Computing Dr. Nadeem A Khan. Lecture 11.

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