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There are many types of data that we come across in our daily life. For example, we need to handle data such as names, addresses, money, date, stock quotes, statistics and etc everyday. Similarly in Visual Basic, we have to deal with all sorts of of data. VB divides data into different types so that it is easier for us to manage. 5.1 Types of Visual Basic Data 5.1.1 Numeric Data Numeric data are data that consist of numbers, which can be computed mathematically with various standard operators such as add, minus, multiply, divide and so on. In Visual Basic, numeric data are divided into 7 types, they are summarized in Table 5.1 5.1.2 Non-numeric Data Types Nonnumeric data types are data that cannot be manipulated mathematically using standard arithmetic operators. They are summarized in Table 5.2
5.1.3 Suffixes for Literals Literals are values that you assign to a data. In some cases, we need to add a suffix behind a literal so that VB can handle the calculation more accurately. For example, we can use num=1.3089# for a Double type data. Some of the suffixes are displayed in Table 5.3. Table 5.3
In addition, we need to enclose string literals within two quotations and date and time literals within two # sign. Strings can contain any characters, including numbers. The following are few examples: memberName="Turban, John." |
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5.2 Managing Variables
Variables are like mail boxes in the post office. The contents of the variables changes every now and then, just like the mail boxes. In term of VB, variables are areas allocated by the computer memory to hold data. Like the mail boxes, each variable must be given a name. To name a variable in Visual Basic, you have to follow a set of rules.
5.2.1 Variable Names
The following are the rules when naming the variables in Visual Basic
Examples of valid and invalid variable names are displayed in Table 5.4
Table 5.4
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Valid Name |
Invalid Name |
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My_Car |
My.Car |
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ThisYear |
1NewBoy |
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Long_Name_Can_beUSE |
He&HisFather *& is not acceptable |
5.2.2 Declaring Variables
In Visual Basic, one needs to declare the variables
before using them by assigning names and data types. They are normally declared
in the general section of the codes' windows using the Dim statement.
The format is as follows:
Dim variableNmae as DataType
Example 5.1
Dim password As String
Dim yourName As String
Dim firstnum As Integer
Dim secondnum As Integer
Dim total As Integer
Dim doDate As Date
You may also combine them in one line , separating each variable with a comma, as follows:
Dim password As String, yourName As String, firstnum As Integer,.............
If data type is not specified, VB will
automatically declare the variable as a Variant.
For string declaration, there are two possible
formats, one for the variable-length string and another for the fixed-length
string. For the variable-length string, just use the same format as example 5.1
above. However, for the fixed-length string, you have to use the format as shown
below:
Dim VariableName as String * n, where n defines the number of characters the string can hold.
Example 5.2:
Dim yourName as String * 10
yourName can
holds no more than 10 Characters.