Lecture 3 Variables,Constants,Calculations EDITED

7/25/2019 Lecture 3 Variables,Constants,Calculations EDITED

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LECTURE 3


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Temporary memory locations that have: a name

a data type, and

a scope.The name given to the location is called

identifer. The value stored in a variable can be changed

during the execution o the project

The values stored in constantscannotchange


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!ariables and "amed #onstants must bedeclared beore being used in code

$hen you declare a !ariable or "amed#onstant !%

&eserves an area o memory

'ssigns it a name called an (dentifer

)eclaration statements are coded either

%eginning o a procedure

*eneral )eclarations o a module


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DIMused to declare !ariables CONSTused to declare "amed #onstants )eclaration includes

"ame, ollo "aming #onvention &ules

)ata Type

&euired !alue or #onstants

ptional (nitial !alue or !ariables


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Boolean

Byte (0 to 255)

Char

Date

String

Decimal

Object Short (-32,768 to 32,767)

nteger

!("2,#$7,$8%,6$8 to

2,#$7,$8%,6$7)

&ong (larger 'holenmber)

Single (*loating +oint accracy to 6

igit) Doble

!(*loating +oint accracy to 14

+oint)


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%oolean 1 2 bytes %yte 1 byte #har 1 2 bytes

)ate 1 bytes 4tring 1 varies )ecimal 1 0 bytes bject 1 + bytes

4hort 1 2 bytes (nteger 1 + bytes 5ong 1 bytes

4ingle 1 + bytes )ouble 1 bytes


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%oolean 1 bln %yte 1 byt #har 1 chr

)ate 1 dat 4tring 1 str )ecimal 1 dec bject 1 depends

on type o object

4hort 1 sht (nteger 1 int 5ong 1 lng

4ingle 1 sng )ouble 1 dbl


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Dim strName, strSSN As StringDim intAge As Short

DimdecPayRate As Decima ! "#$%InitializationDim dat&ireDate As DateDim 'nIns(red As )ooeanDim ngPo*(ation As Long

ConstdecDISCOUNT+RATE As Decima ! #%Fixed

Note:Constants are named using all uppercase

letters EXCEPT the prefix.


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#alculations can be perormed usingproperties o certain objects, variables,constants, and numeric literals

)o "ot use 4trings in calculations !alues rom Text property o Text %oxes 're 4trings, even i they contain numeric data

8ustbe converted to a "umeric )ata Type


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#alculations may be perormedusing the values o

numeric variables,

constants, and

properties o controls.

The result o a calculation may be

assigned toa n(meric -aria'e orto the *ro*erty o. a contro#


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unctions perorm an action and return avalue

;xpression to operate on is called the

'rgument #onversion unctions convert arguments into

a numeric value o the correct data type

#onversion unctions on Text %oxesailiuser enters nonnumeric data or leaves the

Text %ox blan

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Lecture 3 Variables,Constants,Calculations EDITED