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Data Types - Data Types
Data Types
As you may have noticed, VB supports several data types. These are
what the main 'Types' that you can declare your variables as. For example:
Dim intCount As Integer
is an Integer. You always should tell Visual Basic what sort of data
the variable will hold. This will make your code easier to use, and
will also save memory. Different types of variables need different amounts
of memory. You need to use the smallest amount of memory. For example,
if you will need to store a number from 0 - 255 in a variable, you can
save memory by declaring it as a Byte (1 byte) rather than as an Integer
(2 bytes). This is not really very much memory, but if you are untidy
with all your variables, your application will use much more memory
than it has to.
The table below lists the various Data Types, what data they can store
and how many bytes they use.
|
Data type
|
Storage size
|
Range
|
|
Byte
|
1 byte
|
0 to 255
|
|
Boolean
|
2 bytes
|
True or False
|
|
Integer
|
2 bytes
|
-32,768 to 32,767
|
|
Long (long integer)
|
4 bytes
|
-2,147,483,648 to 2,147,483,647
|
|
Single (single-precision floating-point)
|
4 bytes
|
-3.402823E38 to -1.401298E-45 for negative values; 1.401298E-45
to 3.402823E38 for positive values
|
|
Double (double-precision floating-point)
|
8 bytes
|
-1.79769313486232E308 to -4.94065645841247E-324 for negative
values; 4.94065645841247E-324 to 1.79769313486232E308 for positive
values
|
|
Currency (scaled integer)
|
8 bytes
|
-922,337,203,685,477.5808 to 922,337,203,685,477.5807
|
|
Decimal
|
14 bytes
|
+/-79,228,162,514,264,337,593,543,950,335 with no decimal point;
+/-7.9228162514264337593543950335 with 28 places to the right
of the decimal; smallest non-zero number is +/-0.0000000000000000000000000001
|
|
Date
|
8 bytes
|
January 1, 100 to December 31, 9999
|
|
Object
|
4 bytes
|
Any Object reference
|
|
String (variable-length)
|
10 bytes + string length
|
0 to approximately 2 billion
|
|
String (fixed-length)
|
Length of string
|
1 to approximately 65,400
|
|
Variant (with numbers)
|
16 bytes
|
Any numeric value up to the range of a Double
|
|
Variant (with characters)
|
22 bytes + string length
|
Same range as for variable-length String
|
James first started writing tutorials on Visual Basic in 1999 whilst starting this website (then known as VB Web). Since then, the site has grown rapidly, and James has written numerous tutorials, articles and reviews on VB, PHP, ASP and C#. In October 2003, James formed the company Developer Fusion Ltd, which owns this website, and also offers various development services. In his spare time, he's a 3rd year undergraduate studying Computer Science in the UK. He's also a Visual Basic MVP.
Comments
-
Posted by gena_st on 25 Feb 2004
i would be interested in a list of data-type-specific operators. for example, in an if...then statement, what operator do i use to compare one string to another? what operator is used to multiply two... -
Posted by Robin Murfin on 30 Jan 2004
I have heard that using the smallest datatype in a program does not necessarily save space in memory, as memory is optimised to work in blocks of a certain size, possibly VB Long.
Is this correct, ...
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