Data Types of Visual Basics 6.0 and its examplesAssignment no.2

10/22/2013

SUBMITTED BY : HUSSAIN HAKIM ALI KHAN

SUBMISSION TO: SIR ASIM IFTIKHAR

DATE OF SUBMISSION: 22 OCTOBER 2013

ID CARD #: 2011-1-92-13523

SECTION: A

Visual Basic/Data Types with examplesData types in Visual Basic can be divided into three groups:

Native: Types that are understood directly by the Visual Basic compiler without assistance from the

programmer

User-defined: commonly referred to by the initials UDT, meaning User defined Type, these

correspond to Pascal records or C structs

Classes: the basis for object oriented programming in Visual Basic. Classes include forms, add-ins,

and database designers.

Built in Types

The built in types are:

Byte

8 bit, unsigned

Integer

16 bit, signed

Long

32 bit signed

Single

32 bit floating point, range about 

Double

64 bit IEEE floating point, range about 

Currency

exact representation of decimal numbers of up to four decimal places

String

dynamically allocated UniCode strings, theorectical capacity about   characters.

Collection

an associative array of Variants.

Date

8 byte date/time value range January 1, 100 to December 31, 9999

Object

a holder for any type of Object.

Variant

a holder for any type of value or object.

Byte, Integer & Long

Example:

Dim a as Byte

Dim i as Integer

Dim x,y as Long 'Define two variables. Note that only the last variable will be a

long integer.

Now those variables will only be capable of storing integer values (without decimal). Long integers can

store a number with a bigger range of value than integers but they occupy a bigger space of RAM.

Type Storage Range of Values

Byte 1 byte 0 to 255

Integer 2 bytes -32,768 to 32,767

Long 4 bytes -2,147,483,648 to 2,147,483,647

Single & Double

These data types can

store decimal

values. "Double"

compared to "Single" is

similar to the "Long"

compared to "Integer".

Round() rounds off a

decimal to a certain

Type Storage

Single Range of Values

Double-3.402823E+38 to -1.401298E-45 for negative values

1.401298E-45 to 3.402823E+38 for positive values.

-1.79769313486232e+308 to -4.94065645841247E-324 for negative values

4.94065645841247E-324 to 1.79769313486232e+308 for positive values.

number of decimal digits that the programmer wants. The first argument should be a decimal value which you

want to round off. The second argument specifies the number of decimal digits you want, for example:

Dim pi as Double

pi=3.141592653589

pi=Round(pi,2) 'Rounds off 3.141592653589 to only two decimal digits

Print pi 'Prints 3.14

String

A string is an array of characters. As an example:

Dim a As String

a = "This is a string"

Strings can be concatenated (connected together to form a new string) using the "&" operator. For example,

dim b as String

b = "Wiki" & "book" & "s"

Print b 'Prints "Wikibooks"

A normal string variable occupies 10 bytes of RAM, plus the string's size, and can hold up to 2 billion

characters!

Structure

An example definition of a structured type:

Type E2Point

x As Double

y As Double

End Type

Sub Test()

Dim MyPoint As E2Point

Dim MyPoint2 As E2Point

MyPoint.x = 4

MyPoint.y = -5

MyPoint2 = MyPoint 'Make a copy

MyPoint2.x = 3

MyPoint2.y = -6

Debug.Print MyPoint.x, MyPoint.y '4, -5

not overriden with 3 and -6

Debug.Print TypeOf MyPoint Is E2Point 'True

Debug.Print TypeOf MyPoint Is Object 'False

End Sub

The type has to be defined outside of a procedure.

A variable of a structure type is not an object.

Enumeration

An example definition of an enumerated type:

Enum Colors

Red '=0

Green '=1

Blue '=2

End Enum

Enum Colors2

Red2 = 1

Green2 '=2

Blue2 '=3

End Enum

Sub Test()

Debug.Print Red, Green, Blue

Debug.Print Red2, Green2, Blue2

Dim MyVar As Colors 'Ends up being typed as Long

MyVar = 8 'Does not lead to an error: no restriction on values

End Sub